Collins Cobuild English Grammar

photo photos radio radios

However, the following nouns ending in o have plurals ending in oes :

domino

echo

embargo

hero

negro

potato

tomato

veto

The following nouns ending in o have plurals that can end in either s or es:

buffalo

cargo

flamingo

fresco

ghetto

innuendo

mango

manifesto

memento

mosquito

motto

salvo

stiletto

tornado

torpedo

volcano

R12    The following nouns in English have special plural forms, usually with different vowel sounds from their singular forms:

child children foot feet goose geese louse lice man men mouse mice ox oxen tooth teeth woman women

R13    Most nouns that refer to people and that end with man, woman, or child have plural forms ending with men, women, or children.

postman postmen Englishwoman Englishwomen grandchild grandchildren

R14    In addition to the nouns mentioned above, there are words that are borrowed from other languages, especially Latin, and that still form their plurals according to the rules of those languages. Many of them are technical or formal, and some of those that are given below are also used with a regular s or es plural ending in non-technical or informal contexts. You may need to check these in a Cobuild dictionary.

R15    Some nouns ending in us have plurals ending in i.

cactus cacti focus foci nucleus nuclei radius radi stimulus stimuli

R16    Some nouns ending in um have plurals ending in a.

aquarium aquaria memorandum memoranda referendum referenda spectrum spectra stratum strata

R17    Most nouns ending in is have plurals in which the is is replaced by es.

analysis analyses axis axes basis bases crisis crises diagnosis diagnoses hypothesis hypotheses neurosis neuroses parenthesis parentheses

R18    With some nouns ending in a, the plurals are formed by adding e.

larva larvae vertebra vertebrae

Some, such as antenna, formula, amoeba, and nebula, also have less formal plurals ending in s.

R19    Other nouns form their plurals in other ways. Some of these have two plural forms, one formed with s and one formed in a different way. Usually the form with s is used in less formal English.

appendix appendices or appendixes automaton automata or automatons corpus corpora or corpuses criterion criteria genus genera index indices or indexes matrix matrices phenomenon phenomena tempo tempi or tempos virtuoso virtuosi or virtuosos vortex vortices

Forming comparative and superlative adjectives

R20    Information on how to use the comparatives and superlatives of adjectives is given in Chapter 2 (2.103 to 2.122).

R21    The comparative of an adjective is formed either by adding er to the end of the normal form of the adjective, or by putting more in front of it. The superlative is formed by adding est to the end of the adjective, or by putting most in front of it.

The choice between adding er and est or using more and most usually depends on the number of syllables in the adjective.

Superlatives are usually preceded by the.

R22    With one-syllable adjectives, you usually add er and est to the end of the normal form of the adjective.

tall taller the tallest quick quicker the quickest

Here is a list of common one-syllable adjectives that form their comparatives and superlatives usually, or always, by adding er and est:

big

bright

broad

cheap

clean

clear

close

cold

cool

cross

dark

deep

dry

dull

fair

fast

fat

fine

firm

flat

fresh

full

great

hard

high

hot

large

late

light

long

loose

loud

low

new

nice

old

pale

plain

poor

proud

quick

rare

rich

rough

sad

safe

sharp

short

sick

slow

small

soft

strong

sweet

tall

thick

thin

tight

tough

warm

weak

wet

wide

wild

young

Note that when er and est are added to some adjectives, a spelling change needs to be made.

The patterns of spelling change in forming comparatives and superlatives from adjectives are explained in paragraph R27.

R23    You usually add er and est to two-syllable adjectives ending in y, such as funny, dirty, and silly.

happy happier the happiest easy easier the easiest

Note that there is a spelling change here, which is explained in paragraph R27.

Some other two-syllable adjectives, not ending in y, also have comparatives and superlatives that are usually formed with er and est.