Inflection of the Scottish Gaelic lexeme for "dog", which is for singular, chù for dual with the number ("two"), and coin for plural

In morphology, inflection (or inflexion) is a process of word formation,[1] in which a word is modified to express different grammatical categories such as tense, case, voice, aspect, person, number, gender, mood, animacy, and definiteness.[2] The inflection of verbs is called conjugation, and one can refer to the inflection of nouns, adjectives, adverbs, pronouns, determiners, participles, prepositions and postpositions, numerals, articles etc., as declension.

An inflection expresses grammatical categories with affixation (such as prefix, suffix, infix, circumfix, and transfix), apophony (as Indo-European ablaut), or other modifications.[3] For example, the Latin verb ducam, meaning "I will lead", includes the suffix -am, expressing person (first), number (singular), and tense-mood (future indicative or present subjunctive). The use of this suffix is an inflection. In contrast, in the English clause "I will lead", the word lead is not inflected for any of person, number, or tense; it is simply the bare form of a verb.

The inflected form of a word often contains both one or more free morphemes (a unit of meaning which can stand by itself as a word), and one or more bound morphemes (a unit of meaning which cannot stand alone as a word). For example, the English word cars is a noun that is inflected for number, specifically to express the plural; the content morpheme car is unbound because it could stand alone as a word, while the suffix -s is bound because it cannot stand alone as a word. These two morphemes together form the inflected word cars.

Words that are never subject to inflection are said to be invariant; for example, the English verb must is an invariant item: it never takes a suffix or changes form to signify a different grammatical category. Its categories can be determined only from its context. Languages that seldom make use of inflection, such as Standard Chinese, are said to be analytic or isolating.

Requiring the forms or inflections of more than one word in a sentence to be compatible with each other according to the rules of the language is known as concord or agreement. For example, in "the choir sings", "choir" is a singular noun, so "sing" is constrained in the present tense to use the third person singular suffix "s". The sentence *"the choir sing" is not grammatically correct in English.[a]

Languages that have some degree of inflection are synthetic languages. These can be highly inflected (such as Latin, Greek, Spanish, Biblical Hebrew, and Sanskrit), or weakly inflected (such as English). Languages that are so inflected that a sentence can consist of a single highly inflected word (such as many American Indian languages) are called polysynthetic languages. Languages in which each inflection conveys only a single grammatical category, such as Finnish, are known as agglutinative languages, while languages in which a single inflection can convey multiple grammatical roles (such as both nominative case and plural, as in Latin and German) are called fusional.

Examples in English

In English most nouns are inflected for number with the inflectional plural affix -s (as in "dog" → "dog-s"), and most English verbs are inflected for tense with the inflectional past tense affix -ed (as in "call" → "call-ed"). English also inflects verbs by affixation to mark the third person singular in the present tense (with -s), and the present participle (with -ing). English short adjectives are inflected to mark comparative and superlative forms (with -er and -est respectively).

There are 9 inflectional affixes in the English language.[citation needed]

Inflectional Affixes in English
Affix Grammatical Category Mark Part of Speech
-s Number plural nouns
-'s/'/s Case genitive nouns and noun phrases, pronouns (marks independent genitive)
-self Case reflexive pronoun
-ing Aspect progressive verbs
-en/-ed Aspect perfect non-progressive verbs
-ed Tense past (simple) verbs
-s Person, Number, Aspect, Tense 3rd person singular present verbs
-er Degree of Comparison comparative adjectives (monosyllabic or ending in -y or -i.e.)
-est Degree of Comparison superlative adjectives

Despite the march towards regularization, modern English retains traces of its ancestry, with a minority of its words still using inflection by ablaut (sound change, mostly in verbs) and umlaut (a particular type of sound change, mostly in nouns), as well as long-short vowel alternation. For example:

  • Write, wrote, written (marking by ablaut variation, and also suffixing in the participle)
  • Sing, sang, sung (ablaut)
  • Foot, feet (marking by umlaut variation)
  • Mouse, mice (umlaut)
  • Child, children (ablaut, and also suffixing in the plural)

For details, see English plural, English verbs, and English irregular verbs.

Other Languages
Afrikaans: Verbuiging
العربية: تصريف (لغة)
беларуская: Словазмяненне
беларуская (тарашкевіца)‎: Словазьмена
Boarisch: Flexion
català: Flexió
čeština: Ohýbání
Cymraeg: Ffurfiant
Deutsch: Flexion
Esperanto: Fleksio
euskara: Flexio
فارسی: تصریف
ქართული: ფლექსია
Latina: Flexura
magyar: Flexió
Nederlands: Flexie (taalkunde)
日本語: 語形変化
norsk: Bøying
norsk nynorsk: Bøying
polski: Fleksja
română: Flexiune
саха тыла: Флексия
Seeltersk: Beegenge
Simple English: Inflection
Türkçe: Çekim eki
українська: Словозміна
Tiếng Việt: Biến tố
中文: 词形变化