Inflection is the name for the extra letter or letters added to nouns, verbs and adjectives in their different grammatical forms. Nouns are inflected in the plural, verbs are inflected in the various tenses, and adjectives are inflected in the comparative/superlative. Here are some of the most important inflection rules:
| Original word type | Inflection Rule | Examples |
| Words ending with a sibilant: -s/-ss/-sh/-ch/x. Words ending with the letter -o. |
Add -es in the plural noun or 3rd person singular verb. | bus → buses (n) / busses (v) miss → misses wish → wishes watch → watches fox → foxes potato → potatoes do → does |
| Words ending consonant - y. | Change the -y to ie before the ending -s. | party → parties study → studies cry → cries |
| Words ending consonant - y. | Change the -y to i before the endings -ed/-er/-est/-ly. | try → tried happy → happier easy → easiest |
| Words ending consonant - y. | Do NOT change the -y before the ending -ing. | carry → carrying try → trying |
| Words ending vowel - y. | Do NOT change the -y. | buy → buys play → played |
| Words ending with the letters -ie. | Change the -ie to a - y before the ending -ing. | die → dying lie → lying |
| Verbs ending consonant -e. | Omit the -e before the ending -ing. | ride → riding love → loving write → writing provide → providing |
| One-syllable words ending
consonant-vowel-consonant. Two or more syllable words ending consonant-vowel-consonant that are stressed on the last syllable. |
Double the last consonant before the endings -ing/-ed/-er/-est. | hit → hitting stop → stopped wet → wetter fat → fattest begin → beginning prefer → preferred |
| Two or more syllable words ending consonant-vowel-consonant that are stressed on the first syllable. | Do NOT double the last consonant before the endings -ing/-ed/-er/-est. | happen → happening visit → visited |
