1. When the added sound of "s" makes an additional syllable, "es" is used: as, box, boxes; church, churches.
2. Nouns ending in "o." If the final "o" is preceded by a vowel, the plural is formed regularly, i.e., by adding "s": as, cameo, cameos. If the final "o" is preceded by a consonant, the tendency of modern usage is to form the plural by adding "es": as, hero, heroes; potato, potatoes. The following common words, however, seem still to form the plural by adding "s" alone:—
| canto | lasso | proviso | torso |
| duodecimo | memento | quarto | tyro |
| halo | octavo | solo | |
| junto | piano | stiletto |
3. Nouns ending in "y." If the "y" is preceded by a vowel, the plural is regular: as, valley, valleys.
If the "y" is preceded by a consonant, "y" is changed to "i" and "es" is added to form the plural: as, lady, ladies; city, cities.
4. Proper nouns are changed as little as possible: as, Henry, Henrys; Mary, Marys; Cicero, Ciceros; Nero, Neros.
5. Most compound nouns form the plural by adding the proper sign of the plural to the fundamental part of the word, i.e., to the part which is described by the rest of the phrase: as, ox-cart, ox-carts; court-martial, courts-martial; aide-de-camp, aides-de-camp.
Note the difference between the plural and the possessive of compound nouns,—forms which are often confounded. See page 16.
6. Letters, figures, and other symbols are made plural by adding an apostrophe and "s" ('s): as, "There are more e's than a's in this word"; "Dot your i's and cross your t's."
7. Some nouns have two plurals, which differ in meaning:—
| Singular. | Plural. |
| brother | brothers (by birth), brethren (of a society). |
| die | dies (for coining or stamping), dice (for play). |
| fish | fishes (separate fish), fish (collective). |
| index | indexes (in books), indices (in algebra). |
| penny | pennies (separate coins), pence (sum of money). |
| shot | shots (discharges), shot (balls). |
| staff | staves (poles), staffs (bodies of assistants). |
[15] "Foundations," pp. 45-47.
EXERCISE XI.[16]
Write the plural of: Lash, cage, race, buffalo, echo, canto, volcano, portfolio, ally, money, solo, memento, mosquito, bamboo, ditch, chimney, man, Norman,[17] Mussulman, city, negro, baby, calf, man-of-war, attorney, goose-quill, canon, quail, mystery, turkey, wife, body, snipe, knight-errant,[17] donkey, spoonful, aide-de-camp, Ottoman, commander-in-chief, major-general, pony, reply, talisman, court-martial, father-in-law, court-yard, man-trap, Brahman, journey, Henry, stepson, deer, mouthful, Miss Clark,[18] Mr. Jones, Dr. Brown, Dutchman, German, forget-me-not, poet-laureate, minister-plenipotentiary, hero, fish, trout, Mary, George, bill-of-fare.
[16] To THE TEACHER.—To have its full value this should be given as a dictation exercise.
[17] Consult a dictionary for this and similar nouns.
[18] Proper names preceded by a title are made plural by changing either the name or the title, and using "the" before the expression. We may say "the Miss Smiths" or "the Misses Smith," "the Doctors Young" or "the Doctor Youngs."
EXERCISE XII.
Distinguish between:—