- we usually, but not always, add -s: friend – friends; book – books; 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;
 Irregular plurals
For historical reasons a few plurals are irregular.
- No plural. Usually animals - Sheep, swine, deer.
- ves to words ending –f/fe: wife – wives; knife – knives; life – lives; loaf - loaves, but note the following: beliefs, chiefs, dwarfs, gulfs, proofs, roofs).
- en - people and some animals. child – children; man – men; woman - women; ox - oxen.
- others: tooth – teeth;
Note: some nouns ending in -s are mass nouns: measles – a news item – mathematics - physics – politics – a TV series;