1. For a single syllable word, ending in a single consonant preceded by a single vowel - double the consonant:
swim; swimmer; swimming
rob, robber, robbed, robbing
2. For a single syllable word, ending in a single consonant preceded by two vowels - do NOT double the consonant:
meet, meeting
pair, paired, pairing
3. For a multiple syllable word, ending in a single consonant preceded by a single vowel, if stress is on last syllable, double the consonant:
prefer, preferred, preferring
4. For most words, add -s to the singular form to make it plural:
cat, cats; bell, bells; rose, roses
5. If a word ends in vowel + o, usually add -s to form the plural:
monkey, monkeys (BUT money, moneys, OR monies). If a word ends in a consonant + o, sometimes add -s:
piano, pianos
OR sometimes add -es:
potato, potatoes
OR sometimes add either:
zero, zeros, zeroes
6. If a word ends in f or fe, sometimes add -s to make it plural:
roof, roofs OR sometimes change f or fe to -ves:
half, halves; wife, wives
OR sometimes add either:
scarf, scarfs, scarves
7. Add -es to the singular form when it ends in s, ss, ch, sh, x, z, or zz:
bus, buses
kiss, kisses
church, churches
bush, bushes
ax, axes
waltz, waltzes
fizz, fizzes
8. Drop the final -e if a suffix* begins with a vowel:
desire, desiring, desirable
9. Keep the final -e if a suffix begins with a consonant:
care + full = careful
complete + ly = completely
excite + ment = excitement
10. For a word that ends in a consonant + y, change the -y to -i for most suffixes:
pony, ponies
deny, denies
denied
11. If a word ends in -ay, -ey, -oy, form the plural by simply adding -s:
ray, rays
valley, valleys
toy, toys
12. Sometimes you change -ie to -y before -ing:
die, died, dying
lie, lied, lying
13. The sound of "shun" has several different spellings:
solution, occasion, mission, musician, Dalmatian, crucifixion
14. The following prefixes** give negative meaning to the original word:
unhappy
invisible
illegal
impolite
irregular
*A suffix is a word ending. It changes the part of speech of the word, but does not change the meaning of the original ("root") word entirely: see, seeing;
act, actor
beauty, beautiful
equip, equipment
** A prefix is a word beginning. It changes the meaning of the original ("root") word:
review
preview
foresee
coworker
Singular, Plural of some words
alumna, alumnae
alumnus, alumni
analysis, analyses
auditorium, auditoriums
bacterium, bacteria
box, boxes
child, children
crisis, crises
crisis, crises
deer, deer/deers
fish, fish/fishes
foot, feet
fungo, fungoes
goose, geese
house, houses
man, men
milk, -
mother-in-law, mothers-in-law
mouse, mice
ox, oxen
-, pants
-, people
physics, -
-, scissors
sheep, -
sock, socks/sox
tooth, teeth
woman, women