Definition from Wiktionary, the free dictionary
- (grammar): A way of categorizing nouns, pronouns, or adjectives according to the inflections they receive.
- In Latin, 'amicus' belongs to the second declension. Most second-declension nouns end in '-i' in the genitive singular and '-um' in the accusative singular.
- (grammar): The act of declining a word; the act of listing the inflections of a noun, pronoun or adjective in order.
Coordinate terms 
Derived terms 
a way of categorizing nouns
act of declining