Mysteries solved! Secrets of the perplexing apostrophe

Whether it’s used in contractions or plural possessives—or omitted from plurals and possessive pronouns—this little curl can bring big headaches. Here are a few ounces of prevention.

Apostrophe use can confuse even seasoned writers.

This post discusses the three primary functions of the apostrophe in English: the marking of the possessive case in nouns, the marking of the omission of one or more letters, and the marking of plurals of individual characters. (The obsolescence of apostrophes with abbreviations is also discussed.)

Marking possessives

Apostrophes are employed in conjunction with the possessive s, as shown in the following examples:

  • singular common nouns: “the farmer’s daughter”
    • singular proper nouns that end in s: “Chris’ job” or “Chris’s job” (depending on which style one employs)
    • plural common nouns: “the farmers’ daughters”
    • plural common nouns that end in s: “the dogs’ bowls”
    • plural proper nouns ending in s: “the Thompsons’ party” (no sat the end of the name); “the Simmonses’ car” (sat the end of the name)
    • compound words: “mother-in-law’s tongue”
    • separate possession: “John’s and Jane’s houses”
    • joint possession: “John and Jane’s house”

Note, in the case of proper nouns ending in s, the distinction between the first example, which refers to a party hosted by the Thompson family, and the usage Thompson’s, which refers to something belonging to a particular Thompson.

Lack of attention to this distinction is the cause of frequent errors in signage, as when a sign referring to the inhabitants of a residence reads, “The Thompson’s.” This truncation of “the Thompson’s house” literally indicates that it is the house of the Thompson and therefore is incorrect; it should read, “The Thompsons’.”

Irregular plural nouns such as mice are treated according to the pertinent rule above, as in “The mice’s whiskers twitched with curiosity.” Also, nouns that are plural in form but singular in meaning technically take an apostrophe with no s (“the scissors’ handle,” though “the handle of the scissors” is easier to read and say). This rule applies to similar proper nouns (“Highland Estates’ bylaws”). Another exception is in the phrase “for goodness’ sake.”

Attributive forms, as opposed to possessive forms, do not take an apostrophe (“veterans affairs”). The distinction is subtle, but test for the correct form by determining whether the phrase refers to an entity that exists for a given group (“veterans affairs”) or belongs to it or is organized by it (“farmers’ market”).

Names of holidays should be styled according to who or what they honor: “Mother’s Day” is treated as such, for example, because although the day is for all mothers, one traditionally honored only one’s own mother, while Presidents’ Day commemorates all presidents. (“Veterans Day” is an anomaly.)

Insertion or omission of apostrophes is also inconsistent in proper names in general, especially in geographical locations (“Pikes Peak,” but “Martha’s Vineyard’) or names of entities such as companies and organizations (Barclays, but McDonald’s).

When an italicized term takes the possessive form, the apostrophe and the s are not italicized (as in “The Wizard of Oz‘s enduring charm”).


Apostrophes mark elision of one or more letters or numbers, as shown in the following examples:

  • don’t (“do not”)
    o’clock(“of the clock”)
    c’mon (“come on”)
    let’s (“let us”)
    li’l (little)
    OK’d (in place of OKed)
    ’tis (“it is”)
    will-o’-the-wisp (will-of-the-wisp)
    • “rock ‘n’ roll” (“rock and roll”)
    fo’c’stle (forecastle)
    O’Hara (“of the Hara,” from Gaelic Eaghra)
    ’60s (1960s)

Many writers are confused about this function in some usage, erroneously apostrophizing possessive pronouns such as its (resulting in the erroneous it’s) and plural nouns such as apples (confusing them for possessive forms, as in a sign reading “Apple’s on sale”).

Also, plural possessives pertaining to time frames are often mistakenly rendered as singular possessives (“two week’s notice”) or as plurals (“two weeks notice”); the proper form is “two weeks’ notice,” because the notice “belongs” to two weeks. (Note, however, the absence of an apostrophe in the phrase “two weeks late” because weeks is plural but not possessive.)

Another frequent error is confusion of use of the apostrophe as the first character in a term. When contracting a word by beginning with an apostrophe, as in ’tis and “rock ‘n’ roll,” or when contracting a number representing a four-digit year to the last two digits, as in the last example in the list above, precede it with an apostrophe—not an open single quotation mark (‘)—but indicate a range of years with a plural s alone (1960s), not with an apostrophe and an s ; reserve that form for possessives (“1960’s most significant event,” in which a year, not a decade, is under discussion).

Also, an apostrophe should follow a number, whether spelled out or in numeral form, only in a possessive sense or as a contraction, as in “The 4’s diagonal line is sometimes formed vertically” or “This hundred’s a counterfeit bill.”

Plurals of individual characters

An exception is made for using possessives to indicate plurals of lowercase letters, as in “Mind your p’s and q’s,” “Label the x‘s and y‘s,” and “There are two m‘s in accommodate.”

Also, the first of these examples shows an additional exception, one to the style rule that letters are italicized when employed to refer to themselves, as in “Write an s in the square and an r in the rectangle.” (Normally, plurals of uppercase letters do not feature an apostrophe—and are not italicized—as in “the three Rs” and “I got three As, two Bs, and a C on my report card.” However, Associated Press style differs on those points.)

Apostrophes with abbreviations

Apostrophes at one time were employed with a following s to indicate plurals of nouns styled as initials followed by periods, as in M.D.’s to indicate more than doctor or R.S.V.P.’s to refer to multiple responses to an invitation, because although those forms look awkward, M.D.s and R.S.V.P.s appear even more so. (Writing physiciansand responses will solve that dilemma.)

However, use of periods with initials is becoming obsolete, and an apostrophe in MDs and RSVPs is unnecessary. (Many newer coinages such as CDs and DVDs generally postdate widespread usage of periods in initialisms.)

A version of this post first appeared on Daily Writing Tips .


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