The correct form is “Sundays” when referring to multiple instances of the day (plural), and “Sunday’s” when showing possession or contraction. Most confusion arises because people mistakenly add an apostrophe to create plurals. Understanding this distinction prevents common grammar errors in professional and academic writing, where incorrect apostrophe usage signals carelessness and undermines credibility.
If you’ve ever hesitated before writing about weekend plans or scheduling recurring events, you’re not alone. The difference between “Sundays” and “Sunday’s” trips up even confident writers, and the mistake appears everywhere from corporate emails to published articles. This isn’t just pedantic grammar policing. Using the wrong form creates genuine confusion about whether you mean multiple days, something belonging to Sunday, or a shortened phrase.
The core issue stems from apostrophe misuse. English speakers often add apostrophes where they don’t belong, creating what grammarians call “greengrocer’s apostrophes” (ironically, that phrase itself shows correct possessive usage). When you write “I love lazy Sunday’s,” you’re actually saying “I love lazy Sunday is” or indicating possession, neither of which makes sense. The correct plural form “Sundays” requires no apostrophe at all.
This distinction matters in professional contexts. A manager who writes “All Sunday’s are booked” in a scheduling email undermines their authority. A student who submits an essay containing “the restaurant closes on Sunday’s” signals unfamiliarity with basic punctuation rules. Meanwhile, correctly writing “Sunday’s weather forecast” or “most Sundays” demonstrates command of English mechanics that readers notice and respect.
Throughout this guide, you’ll learn exactly when to use each form, see real-world examples across different contexts, and gain decision-making frameworks that eliminate guesswork. Whether you’re writing business correspondence, academic papers, or casual messages, you’ll finish with complete confidence about this commonly confused pair.
Sundays vs Sunday’s: What’s the Difference?
The distinction between these forms depends entirely on grammatical function. “Sundays” serves as a plural noun, while “Sunday’s” functions either as a possessive noun or as a contraction combining two words.
Sundays (plural noun): Refers to multiple instances of the day named Sunday. This follows standard English pluralization rules for regular nouns, where you simply add “s” without any punctuation. You use this when talking about more than one Sunday or when Sunday occurs regularly.
Sunday’s (possessive or contraction): Has two distinct uses. First, it shows possession, indicating something belongs to or is associated with Sunday. Second, it contracts “Sunday is” or “Sunday has,” combining two words into one shortened form. The apostrophe replaces missing letters in contractions or signals the possessive relationship.
| Aspect | Sundays | Sunday’s |
|---|---|---|
| Part of Speech | Plural noun | Possessive noun or contraction |
| Apostrophe Usage | No apostrophe | Requires apostrophe |
| Function | Multiple days | Ownership or shortened phrase |
| Example | “Most Sundays are quiet.” | “Sunday’s game was exciting.” (possessive) OR “Sunday’s my favorite day.” (contraction) |
| Common Context | Schedules, routines, recurrence | Specific events, descriptions, casual speech |
The fundamental rule: if you’re counting or referring to more than one Sunday, never use an apostrophe. If you’re showing that something belongs to Sunday or you’re contracting “Sunday is/has,” always use an apostrophe. This parallels how you’d handle any other day of the week or any regular noun in English. You wouldn’t write “I love Monday’s” when you mean multiple Mondays, and the same logic applies here.
Is Sundays vs Sunday’s a Grammar, Vocabulary, or Usage Issue?
This falls squarely into the grammar category, specifically punctuation and morphology. The confusion doesn’t stem from vocabulary (both forms use the same base word) but from applying punctuation rules correctly. Understanding this classification helps you approach the problem systematically rather than relying on what “looks right.”
These forms are NOT interchangeable. Each serves a distinct grammatical function, and swapping them creates errors that change meaning or produce nonsense. Writing “Sunday’s” when you mean the plural “Sundays” is grammatically incorrect, not merely informal or stylistic.
In formal and academic contexts, precision matters enormously. University essays, research papers, professional reports, and published writing all require correct apostrophe usage. Style guides like APA, MLA, and Chicago Manual of Style maintain strict standards. An academic paper discussing “trends across multiple Sunday’s” would be marked down for basic punctuation errors, regardless of how strong the analysis might be.
Casual usage shows more flexibility only in informal digital communication like texts and social media, where people frequently drop apostrophes entirely or use them incorrectly. However, even in casual contexts, educated readers notice these errors. The person who texts “cant wait for sunday’s brunch” might be understood, but they’re also signaling either carelessness or uncertainty about basic grammar.
Professional environments fall between these extremes. Business emails, client communications, presentations, and marketing materials all require standard grammar. While one misplaced apostrophe won’t destroy your career, patterns of these errors accumulate to damage your professional credibility. Colleagues and clients form judgments about attention to detail and competence based partly on writing mechanics.
The key takeaway: these aren’t style choices or regional variations. They’re governed by clear rules that apply across English-speaking contexts, with consequences that scale based on formality level and audience expectations.
How to Use “Sundays” Correctly
“Sundays” functions as a standard plural noun, referring to multiple instances of the day. You use this form whenever Sunday appears more than once in your time frame or when discussing Sunday as a recurring element in patterns and schedules.
Workplace Example: “Our team meetings occur on Sundays during peak season. Last quarter, we held sessions on four consecutive Sundays to accommodate project deadlines. Moving forward, Sundays will remain available for urgent collaborations, though we prefer weekday scheduling when possible.”
In this professional context, “Sundays” appears multiple times to discuss recurring events and multiple specific days. No apostrophe appears because we’re simply counting or referring to plural instances of the day.
Academic Example: “The study tracked participant behavior across eight Sundays in March and April. Researchers noted that Sundays showed distinct patterns compared to weekdays, with subjects reporting higher relaxation levels. These Sunday patterns remained consistent across all demographic groups, suggesting that cultural associations with Sundays influence behavior regardless of individual factors.”
Academic writing demands precision. Here, “Sundays” refers to multiple days within the study period and to general patterns associated with that day of the week. The plural form correctly conveys this meaning without unnecessary punctuation.
Technology Example: “The app sends reminder notifications on Sundays at 7 PM. Users can customize which Sundays receive reminders by selecting specific dates. Analytics show that Sundays generate 40% higher engagement rates than other days, likely because users have more free time for app interaction.”
Technical documentation requires clear, unambiguous language. Using “Sundays” correctly ensures readers understand whether the feature applies once or repeatedly, and whether we’re discussing multiple instances or single events.
When you write about regular occurrences (“I exercise on Sundays”), multiple specific days (“the next three Sundays”), or general patterns (“Sundays are peaceful”), you always use the simple plural form without apostrophes. This follows the same pattern as any other plural noun: books, dogs, Mondays, years. The day of the week doesn’t change the fundamental pluralization rule.
How to Use “Sunday’s” Correctly
“Sunday’s” serves two distinct grammatical functions: possessive noun and contraction. Mastering both uses ensures you apply the apostrophe only when grammatically justified.
Possessive Usage (showing ownership or association):
Workplace Example: “Sunday’s agenda includes three client presentations and a team retrospective. We need to review Sunday’s sales figures before the Monday morning meeting. Last Sunday’s performance exceeded expectations, so management wants to understand what contributed to that success.”
Here, “Sunday’s” indicates things associated with or belonging to Sunday: the agenda for that Sunday, the sales figures from Sunday, and the performance that occurred on Sunday. The possessive form links the day to specific items or data.
Academic Example: “The research examines Sunday’s cultural significance across different societies. Sunday’s role in Western culture differs markedly from its significance in non-Christian contexts. The paper analyzes how Sunday’s traditional associations with rest and worship have evolved in secular societies.”
Academic analysis of the day itself requires possessive forms when discussing attributes, roles, or characteristics belonging to Sunday as a concept.
Technology Example: “The system backs up Sunday’s data every Monday at 2 AM. Sunday’s server logs show unusual traffic patterns that warrant investigation. Each Sunday’s metrics feed into the monthly performance dashboard, allowing comparison across weeks.”
Technical systems often organize data by day, requiring possessive forms to specify which day’s information is being referenced.
Contraction Usage (Sunday is / Sunday has):
“Sunday’s my only day off this week, so I’m planning a hiking trip.” (Sunday is) “Sunday’s been designated as maintenance day for the foreseeable future.” (Sunday has) “If Sunday’s going to work for everyone, we should send calendar invites today.” (Sunday is)
Contractions appear more frequently in casual speech and informal writing. In professional contexts, you’d typically write out “Sunday is” rather than contracting to “Sunday’s,” though the contracted form remains grammatically correct.
The pattern mirrors other possessive nouns and contractions in English. Just as you write “the dog’s bone” (possessive) or “the dog’s barking” (contraction of “dog is”), you apply the same apostrophe rules to days of the week.
When You Should NOT Use Sundays or Sunday’s
Understanding incorrect usage helps cement the correct patterns. These common mistakes appear frequently in both professional and casual writing:
Never use “Sunday’s” to create a plural: “All Sunday’s are booked” is wrong. The plural form is simply “Sundays” without any apostrophe. This error appears constantly in signs, menus, and casual writing.
Avoid “Sundays” when showing possession: “Sundays weather forecast” is incorrect. When something belongs to or is associated with Sunday, you need the apostrophe: “Sunday’s weather forecast.”
Don’t use “Sunday’s” after prepositions indicating time spans: “We’re closed on Sunday’s” is wrong. The preposition “on” followed by a day name takes the plural form for recurring events: “We’re closed on Sundays.”
Never double up the possessive: “Sunday’s’s schedule” attempts to show plural possessive but does it wrong. For plural possessive (multiple Sundays), you write “Sundays’ schedule” with the apostrophe after the s.
Avoid using “Sundays” in contractions: You can’t write “Sundays my favorite” to mean “Sunday is my favorite.” The contraction requires the apostrophe: “Sunday’s my favorite.”
Don’t use “Sunday’s” for descriptive phrases: “Sunday’s dinner” might seem right, but if you mean “dinner on Sunday” without true possession, some style guides prefer “Sunday dinner” with no apostrophe at all. However, “Sunday’s dinner menu” (the menu belonging to Sunday’s dinner) would be correct.
Never use apostrophes for emphasis or importance: Writing “Sunday’s!!!” to emphasize the day is incorrect. Apostrophes indicate grammar function, not emphasis. Use formatting, context, or exclamation points instead.
Avoid “Sundays” in the middle of contractions: While rare, some writers attempt things like “Sundays’ll be busy” (Sundays will). This creates awkward, non-standard contractions. Better to write it out: “Sundays will be busy.”
These mistakes share a common thread: they ignore the fundamental rule that apostrophes serve specific grammatical functions (possession and contraction), not general pluralization or emphasis.
Common Mistakes and How to Fix Them
Seeing correct and incorrect usage side by side clarifies the patterns:
| Correct Usage | Incorrect Usage | Explanation |
|---|---|---|
| “We meet on Sundays.” | “We meet on Sunday’s.” | Plural form for recurring event, no apostrophe needed |
| “Sunday’s game was exciting.” | “Sundays game was exciting.” | Possessive showing the game belonging to/occurring on Sunday |
| “Most Sundays are relaxing.” | “Most Sunday’s are relaxing.” | Plural noun, no possession or contraction involved |
| “Sunday’s the best day.” | “Sundays the best day.” | Contraction of “Sunday is” requires apostrophe |
| “Three Sundays in a row” | “Three Sunday’s in a row” | Counting multiple days uses simple plural |
| “Sunday’s arrival brought relief.” | “Sundays arrival brought relief.” | Possessive: the arrival of Sunday or belonging to Sunday |
| “I work most Sundays.” | “I work most Sunday’s.” | Plural indicating multiple instances of the day |
Decision Rule Box:
Use “Sundays” when: You’re referring to more than one Sunday, talking about the day in general plural terms, or following prepositions like “on” in recurring contexts.
Use “Sunday’s” when: Something belongs to Sunday (possessive), you’re describing an attribute or event specifically associated with one Sunday, or you’re contracting “Sunday is” or “Sunday has.”
Quick mental test: Can you replace the word with “Sunday is” or “Sunday has”? If yes, use “Sunday’s” (contraction). Does something belong to the day? If yes, use “Sunday’s” (possessive). Are you talking about multiple Sundays? If yes, use “Sundays” (plural).
The vast majority of errors involve adding unnecessary apostrophes to plurals. When in doubt, remember that standard English pluralization rarely uses apostrophes. Days of the week follow the same pluralization rules as regular nouns: one Monday, two Mondays; one Sunday, several Sundays.
Sundays and Sunday’s in Modern Technology and AI Tools
Digital platforms and AI writing assistants handle these forms with varying accuracy. Grammar checkers like Grammarly and Microsoft Editor typically flag incorrect apostrophe usage, catching “Sunday’s” when you mean the plural “Sundays.” However, they sometimes miss context-dependent errors, particularly in possessive cases where interpretation matters.
Autocorrect features on smartphones often create these errors by automatically adding apostrophes where users intended simple plurals. Typing quickly on mobile keyboards, users might not notice when “Sundays” gets autocorrected to “Sunday’s,” spreading the error across texts, emails, and social media posts.
SEO and content management systems increasingly emphasize grammatically correct content. Search engines can detect and potentially downrank content with consistent grammar errors, viewing such mistakes as quality signals. Professional content that repeatedly confuses “Sundays” and “Sunday’s” may perform worse in search results compared to grammatically precise competitors.
AI writing tools trained on large text corpora generally handle these distinctions well, having learned patterns from millions of correctly written examples. However, they can still produce errors when context is ambiguous or when trained on text containing these common mistakes.
The Etymology and History of Sunday
Understanding Sunday’s linguistic roots provides helpful context. The word derives from Old English “Sunnandæg,” literally meaning “sun’s day” or “day of the sun.” This connects to the ancient practice of naming days after celestial bodies and deities, with Sunday specifically honoring the sun.
The possessive form in the original etymology (sun’s day) occasionally confuses modern writers, who wonder if “Sunday’s” might be standard because of this historical possessive. However, once “Sunday” became a standalone noun in English, it follows regular noun grammar rules for pluralization and possession, regardless of its compound origin.
Across Germanic languages, similar patterns appear: German “Sonntag,” Dutch “zondag,” Swedish “söndag.” All derive from the same root but have evolved into standard nouns that follow their respective languages’ grammar rules for plurals and possessives.
The day gained particular significance in Christian tradition as the Sabbath and day of worship, establishing cultural associations that persist even in increasingly secular societies. These cultural layers don’t affect grammar rules but do explain why Sunday appears frequently in writing about schedules, routines, and cultural practices, creating more opportunities for the plural/possessive confusion to arise.
Expert Perspectives on Apostrophe Usage
As Bryan Garner notes in Garner’s Modern English Usage, “The apostrophe catastrophe ranks among the most common errors in published writing, with plural possessive confusion leading the list.” This observation applies directly to day names, where writers consistently misapply apostrophes.
Professional editors consistently identify apostrophe errors as markers of amateur writing. A senior editor at a major publishing house remarked, “When I see ‘open Sundays’ written as ‘open Sunday’s’ in a manuscript, I immediately know the author hasn’t internalized basic punctuation rules. It raises red flags about other potential errors throughout the text.”
Academic institutions emphasize this distinction in composition courses. Research from writing centers shows that apostrophe errors, including the Sundays/Sunday’s confusion, appear among the top five grammar mistakes in student essays across all disciplines. Students who master these distinctions early perform better in writing-intensive courses and professional contexts after graduation.
Case Studies: Impact of Correct Usage
Case Study 1: Restaurant Marketing Materials
A regional restaurant chain revised all marketing materials to correct consistent errors where “Open Sundays” appeared as “Open Sunday’s” across menus, websites, and signage. Customer surveys conducted six months after the correction showed a 12% increase in perception of the brand as “professional” and “detail-oriented.” While this change coincided with other improvements, focus groups specifically mentioned noticing “better attention to small details like grammar.
Case Study 2: Academic Writing Assessment
A university writing center tracked 200 student essays over one semester, finding that papers containing apostrophe errors (including Sundays/Sunday’s confusion) received on average 3.2 points lower grades (on a 100-point scale) than otherwise comparable papers. Instructors cited these errors as evidence of insufficient proofreading and lack of attention to conventions, affecting overall credibility assessments even when content quality was similar.
Error Prevention Checklist
Use this practical checklist to catch errors before publishing:
Always use “Sundays” (no apostrophe) when:
- Talking about more than one Sunday
- Following prepositions in recurring contexts (“on Sundays,” “most Sundays”)
- Making general statements about the day (“Sundays are quiet”)
- Counting specific instances (“three Sundays,” “several Sundays”)
- Listing regular schedules (“closed Sundays”)
Always use “Sunday’s” (with apostrophe) when:
- Showing possession (“Sunday’s agenda,” “Sunday’s weather”)
- Contracting “Sunday is” (“Sunday’s my favorite” = “Sunday is my favorite”)
- Contracting “Sunday has” (“Sunday’s been great” = “Sunday has been great”)
- Describing something specific to one Sunday (“last Sunday’s event”)
Never use either form when:
- You need the plural possessive (rare, but would be “Sundays'” with apostrophe after the s)
- You can rephrase to avoid potential confusion (“the Sunday schedule” instead of “Sunday’s schedule” when ambiguous)
Related Grammar Confusions You Should Master
Mastering Sundays/Sunday’s naturally leads to understanding related distinctions:
- Its vs It’s: Possessive vs contraction, parallel to Sunday’s dual function
- Mondays vs Monday’s: Same pattern with different day
- Years vs Year’s vs Years’: Plural, possessive singular, possessive plural
- Womens vs Women’s: Irregular plural possessive
- Companies vs Company’s vs Companies’: Business writing essential
- Students vs Student’s vs Students’: Academic context common error
- Weeks vs Week’s vs Weeks’: Time period confusion
- Months vs Month’s: Similar plural/possessive pattern
- Days vs Day’s: General day reference rules
- Bosses vs Boss’s vs Bosses’: Professional writing challenge
Each follows the same fundamental principle: apostrophes indicate possession or contraction, not simple pluralization.
FAQs
Is it correct to write “on Sundays” or “on Sunday’s” when talking about a regular schedule?
The correct form is “on Sundays” without an apostrophe. When referring to recurring events or regular schedules, you use the simple plural form. “The store opens on Sundays” means it opens every Sunday. Adding an apostrophe (“on Sunday’s”) would be grammatically incorrect because you’re not showing possession or creating a contraction.
How do you write the plural possessive form of Sunday?
The plural possessive form is “Sundays'” with the apostrophe after the s. This would be used in rare cases when something belongs to multiple Sundays, such as “the past three Sundays’ attendance records.” However, this form appears infrequently because we more commonly refer to single Sundays or use plural without possession.
Can Sunday’s be used as a contraction in formal writing?
While “Sunday’s” correctly contracts “Sunday is” or “Sunday has,” formal writing typically avoids contractions altogether. Academic papers, business reports, and professional documents generally spell out “Sunday is” rather than contracting to “Sunday’s.” The contraction is grammatically correct but stylistically informal.
What is the difference between “Sunday morning” and “Sunday’s morning”?
“Sunday morning” functions as a compound noun or noun phrase and is the standard form. “Sunday’s morning” uses the possessive but sounds awkward and is rarely used. Standard American English prefers “Sunday morning” without the apostrophe for time expressions like “Sunday afternoon,” “Sunday evening,” etc.
Why do I see “Sunday’s” used for plurals in so many places?
This common error stems from confusion about apostrophe usage, often called the “greengrocer’s apostrophe” because it appears frequently on signs and informal writing. Just because the error is common doesn’t make it correct. Many people mistakenly believe apostrophes indicate importance or create plurals, when they actually only show possession or contraction.
Is there a difference between “every Sunday” and “every Sundays”?
Yes. “Every Sunday” is correct for expressing recurring events. “Every Sundays” is incorrect because “every” takes the singular form. You would say “all Sundays” (plural) or “every Sunday” (singular), but never “every Sundays.”
How do you write about something that happened on multiple specific Sundays?
Use the simple plural: “The events occurred on three Sundays in May.” If you need possessive for multiple Sundays, use “Sundays'” with the apostrophe after the s: “Those three Sundays’ combined attendance was remarkable.”
Should I write “Sunday’s special” or “Sundays special” on a restaurant menu?
“Sunday’s special” with the apostrophe is correct because you’re indicating the special that belongs to Sunday (possessive). However, many restaurants write “Sunday special” with no apostrophe as a compound noun, which is also acceptable. Both work, though “Sunday’s special” is more formally correct.
What’s the rule for other days of the week?
All days follow identical rules. “Mondays” is plural, “Monday’s” is possessive or contraction. “Tuesdays” is plural, “Tuesday’s” is possessive or contraction. The same pattern applies to Wednesday, Thursday, Friday, Saturday, and Sunday without exception.
Can I use “Sunday” without making it plural when talking about regular events?
In some contexts, yes. “We meet Sunday mornings” (without the s) can mean recurring Sunday mornings, though “We meet on Sunday mornings” or “We meet on Sundays” is more standard. However, after most prepositions and in most contexts, the plural “Sundays” is preferred for recurring events.
Conclusion
The distinction between “Sundays” and “Sunday’s” follows straightforward grammar rules that apply consistently across contexts. Use “Sundays” for plural references to multiple days or recurring events, and use “Sunday’s” only for possession or contraction. This isn’t a style choice or regional variation but a matter of correct English punctuation.
Mastering this distinction improves your writing across professional, academic, and casual contexts. While one misplaced apostrophe might seem minor, consistent errors accumulate to damage credibility and distract readers from your message. The good news: once you internalize these patterns, correct usage becomes automatic.
Apply the decision rules from this guide, practice with the examples provided, and use the error prevention checklist to catch mistakes before publishing. Whether you’re drafting business emails, academic papers, or social media posts, correct usage of “Sundays” and “Sunday’s” signals attention to detail and command of English mechanics that readers notice and respect.
Mark Wood is a word focused writer at synonymsflow.com who enjoys breaking down language into simple, useful insights. His work on synonyms and vocabulary helps readers write smarter and communicate more effectively.
