Definition - The systematic modification of pronouns, nouns, and adjectives to show number, case, and gender. For example, using s to show plural.

1. Declensions are arranged in paradigms for pedagogical demonstration.

Etymology -
The word ultimately derives from the Latin noun declinatio (from Latin de, from + clinare, to bend).

Oxford English Dictionary -
Its first citation in its grammatical sense is from 1565:
"Substantives may be perceyved by their gender and declenson."
(Cooper, Thesaurus, Introduction)

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