Inflection, Derivation, Declension, Conjugation

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From a somewhat formal viewpoint, inflection and derivation are morphosyntactic operations in languages.

They visually change a word to mark properties, or relational information, such as number, person and gender, or others.

Inflection and Derivation


  • does not change the lexical category
  • creates grounded forms, and
  • usually creates variations with clear, predictable meanings
in that you'll be able to understand them if you've never seen them before, but you know the base word

A lot of the time this looks largely like predictable affixes.

Sometimes it may change the word further, change pronunciation, and may change interaction (depending on the language).

For example: 'come' → 'comes', variants of the same verb.

Derivation are word changes that (usually) change the lexical category.

Examples: 'joyful' from 'joy', 'amazement' from 'amaze', 'national' from 'nation' (adjectives from nouns).

Derivation may ground, but regularly don't.

These two concepts do not have a strict linguistic definition, and are not the exclusive opposites they are sometimes taken as. Many cases can be said to fall into one or the other, but there are various cases inbetween. As such, judging by earmarks of each is a little more useful.

Conjugation versus Declension

Conjugation and declension refer to specific types of inflection, or rather, that of specific classes:

  • conjugation describes inflection of verbs. In many languages this is more complex than ...
  • declension describes inflection of, well, anything else, usually nouns, but possibly also pronouns, adjectives, determiners, depending on the language.

Languages tend to structurally mark specific properties on specific lexical categories.

For example, many languages conjugate verbs for number, and not unusually for another thing or two.

A language's declension system declines things into different forms while not changing their lexical category, to distinguish certain direct properties such as number and gender, but also case (a.k.a. grammatical case), which is a more relational change.

For example

the accusative case marks the direct object of a transitive verb,
dative to relate to whom something is given,
genitive as a wide/abstract and posessive as a more concrete posession relation between two nouns.


  • German primarily declines nouns, pronouns, articles, and adjectives - for number, gender, and/or case.
  • Modern English primarily just declines nouns for number. It also declines pronouns somewhat. It doesn't decline adjectives.

Modern English declension is perhaps the simplest among Indo-European languages, having use for up to four cases, though regularly not inflecting for them(verify); only grammatical number is systematically declined. Middle and particularly Old English had richer declension.

See also