Some words (lexemes) have more than one word form, depending on the grammatical context or on choices that grammar forces us to make (for example, in nouns, between singular and plural). This kind of word formation is called ‘inflectional’. In so far as grammar affects all words alike, the existence of inflected word forms does not have to be noted in the dictionary; however, the word forms themselves must be listed if they are irregular.

Inflection affects nouns, verbs, adjectives and a few adverbs, as well as the closed classes of pronouns, determiners, auxiliaries and modals. However, the maximum number of distinct inflected forms for any open-class lexeme is small:

nouns:                  2        e.g. cat, cats

verbs:                   5        e.g. gives, gave, giving, given, give

adjectives:           3        e.g. green, greener, greenest

adverbs:               3        e.g. soon, sooner, soonest

Inflection thus plays a much more modest role in modern English than in German (for example), or in Old English. In some languages, a lexeme may have hundreds or even thousands of distinct forms. On the other hand, English makes more use of inflection than languages such as Afrikaans, Vietnamese and Chinese, which have little or none. Why languages should differ so enormously in this respect is a fascinating question, but one that we cannot delve into here.