In linguistic morphology, inflection (less commonly, inflexion) is a process of word formation in which a word is modified to express different grammatical categories such as tense, case, voice, aspect, person, number, gender, mood, animacy, and definiteness. 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.

• Inflections
  • Declension
  • Conjugation
• Change in grammatical categories such as
  • Case , grammatical cases
  • person
  • number
  • gender
  • Tense
  • mood
  • aspect
  • voice
  • definiteness
  • animacy

Languages that add inflectional morphemes to words are sometimes called inflectional languages, which is a synonym for inflected languages. Morphemes may be added in several different ways:

• Affixation, or simply adding morphemes onto the word without changing the root;
• Reduplication, repeating all or part of a word to change its meaning;
• Alternation, exchanging one sound for another in the root (usually vowel sounds, as in the ablaut process found in Germanic strong verbs and the umlaut often found in nouns, among others);
• Suprasegmental variations, such as of stress, pitch or tone, where no sounds are added or changed but the intonation and relative strength of each sound is altered regularly. For an example, see Initial-stress-derived noun.