Student's guide to writing college papers, Fourth edition - Kate L. Turabian 2010

Plurals
Spelling: plurals, possessives, and hyphenation
Style

21.2.1 The General Rule

Most nouns form the plural by adding s.

dog → dogs tree → trees

vehicle → vehicles John → Johns

But there are many irregular nouns that form their plurals in different ways. When in doubt, consult a dictionary.

Do not confuse plurals with possessives. Do not use an apostrophe to make a standard plural:

Plural: dogs, vehicles, Johns

Possessive: dog's, vehicle's, John's

21.2.2 Special Cases

Nouns ending in ch, j, s, sh, x, or z

These nouns add es.

beach → beaches glass → glasses

dish → dishes Alex → Alexes

Common nouns ending in y

If the y is preceded by a vowel, add an s.

boy → boys monkey → monkeys

day → days decoy → decoys

If the y is preceded by a consonant, replaced it with ies.

baby → babies family → families

story → stories hobby → hobbies

Proper nouns ending in y

These nouns add s.

Harry → Harrys Germany → Germanys

Sally → Sallys Jay → Jays

Nouns ending in o

These nouns sometimes add s and sometimes es. If in doubt, check a dictionary.

hero → heroes potato → potatoes

memo → memos auto → autos

Nouns ending in f or fe

These nouns sometimes add s and sometimes replace the f with ves. If in doubt, check a dictionary.

leaf → leaves knife → knives

roof → roofs proof → proofs

Compound Nouns

If the compound is made of two nouns, make the last noun plural. (It does not matter whether the words are joined, hyphenated, or just together.)

bookkeeper → bookkeepers district attorney → district attorneys

actor-singer → actor-singers handyman → handymen

If the compound is made of a noun followed by an adjective or prepositional phrase, make the main noun plural. (It does not matter whether the words are hyphenated or not.)

sister-in-law → sisters-in-law attorney general → attorneys general

man-of-war → men-of-war president-elect → presidents-elect

Letters and Numerals

Numerals and capital letters usually form the plural by adding an s without an apostrophe.

R → Rs 1950 → 1950s

ABC → ABCs 767 → 767s

For lowercase letters or for instances where readers might mistake the plural combination for a word or common abbreviation, add an apostrophe before the s.

j → j's not js I → I's not Is A and B → A's and B's not As and Bs

Abbreviations

If an abbreviation has internal periods or includes both capital and lowercase letters, add an apostrophe plus s.

a.m. → a.m.'s e.g. → e.g.'s PhD → PhD's

Otherwise, add s without an apostrophe. If the abbreviation ends in a period, add the s before the period. (But remember that the plural of p. [page] is pp.)

URL → URLs DVD → DVDs ed. → eds. vol. → vols.

Terms in Italics

For titles and other terms in italics, add s in roman type without an apostrophe.

Chicago Tribune → Chicago Tribunes New Yorker → New Yorkers

Terms in Quotation Marks

Do not form the plural of a term in quotation marks ; rephrase the sentence to avoid the need for a plural.

NOT: included many “To be continued's”

BUT: included “To be continued” many times