declension

Short definition from Wiktionary

Noun

1. 1
   A falling off, decay or descent.
2. 2
   The act of declining a word; the act of listing the inflections of a noun, pronoun or adjective in order.
3. 3
   The product of that act; a list of declined forms.
4. 4
   A way of categorizing nouns, pronouns, or adjectives according to the inflections they receive.