The change of word form according to grammatical function, which occurs in inflected languages.
Inflection is differentiated depending on the class:
- declension, in which a noun changes due to its grammatical function (number, case, or grammatical gender)
- conjugation, in which a verb changes according to number, person (subject or object), tense (time), or mood.
Words often do not appear in a fundamental form (the word root) except in dictionaries and grammars.
The most obvious inflections in English occur in strong verbs, e.g. I am, you are and to take, I took; and nouns, one man, all men; foot, feet. Weak inflections, however, are more common, such as I love, I loved, he loves; John, John's car.