In linguistics, declension (verb: to decline) is the changing of the form of a word, generally to express its syntactic function in the sentence by way of an inflection. Declension may apply to nouns, pronouns, adjectives, adverbs, and determiners. It serves to indicate number (e.g. singular, dual, plural), case (e.g. nominative, accusative, genitive, or dative), gender (e.g. masculine, feminine, or neuter), and a number of other grammatical categories. Inflectional change of verbs is called conjugation.
Declension occurs in many languages. It is an important aspect of language families like Quechuan (i.e., languages native to the Andes), Indo-European (e.g. German, Icelandic, Irish, Lithuanian and Latvian, Slavic, Sanskrit, Latin, Ancient and Modern Greek, Albanian, Romanian, Kurdish, and Modern Armenian), Bantu (e.g. Swahili, Zulu, Kikuyu), Semitic (e.g. Modern Standard Arabic), Finno-Ugric (e.g. Hungarian, Finnish, Estonian), and Turkic (e.g. Turkish).