- we usually add -s:
- pronounced /s/: book - books; night - nights;
- pronounced /z/: friend - friends; eye - eyes;
- -es to words ending in -ch/-x/-s/-sh: watch - watches; box - boxes; glass - glasses; dish - dishes;
- -ies to words ending -y: cherry - cherries; sky - skies;
- Words ending in -o
- Add -es: hero - heroes; potato - potatoes; tomato - tomatoes;
- Add -s: piano - pianos; radio - radios; video - videos;
For historical reasons a few plurals are irregular.
- No plural. Usually animals - sheep, swine, deer.
- Ending in -ves for some words ending –f/fe: half - halves; knife - knives; life - lives; loaf - loaves; shelf - shelves; wife - wives; but note the following: beliefs, chiefs, gulfs, proofs, roofs. The plural of dwarf can be dwarfs or dwarves.
- Ending in /ðz/ for some words ending in /θ/: baths; paths; youths
- Both a regular /θs/ and an irregular /ðz/ plural exist: oaths, truths, wreaths
- others: child – children /tʃaɪld - ˈtʃɪldrən/; foot - feet /fʊt - fiːt/; goose - geese /ɡuːs - ɡiːs/; house - houses /ˈhaʊs - ˈhaʊzɪz/; louse - lice; man – men; mouse - mice; ox - oxen; tooth – teeth; woman - women /ˈwʊmən - ˈwɪmɪn/;
- Plural is different only in written form: chairman - chairmen /ˈtʃeərmən/; milkman - milkmen /ˈmɪlkmən/; postman - postmen /ˈpəʊstmən/
- Singular and plural are spelled identically, but have a different pronunciation: corps /kɔːr, kɔːrz/
- Greek plurals: analysis - analyses /əˈnæləsɪs - əˈnæləsiːz/; basis - bases /ˈbeɪsɪs - ˈbeɪsiːz/; crisis - crises /ˈkraɪsɪs - ˈkraɪsiːz/
- process - processes: This word has a regular plural and irregular ones.
- American English: /ˈprɒses - ˈprɒsesɪz, ˈprɒsəsɪz, ˈprɒsəˌsiːz/;
- Received Pronunciation: /ˈprəʊses - ˈprəʊsesɪz, ˈprəʊsəsɪz/
- axes /ˈæksɪz/ plural of axAmE/axeBrE; /ˈæksiːz/ plural of axis
- bases /ˈbeɪsɪz/ plural of base; /ˈbeɪsiːz/ plural of basis
Some nouns ending in -s are mass nouns: measles – a news item – mathematics - physics – politics – a TV series;
- Random House Dictionary, process. Recent years have seen the increasing popularity of an [-eez] pronunciation for processes, perhaps by mistaken analogy with such plurals as theses and hypotheses, with which it has no connection. Although this newer pronunciation is increasingly common, it is regarded by some educated speakers as an affectation.