Толковый словарь английского языка Oxford English Reference - declension

n. 1 Gram. a the variation of the form of a noun, pronoun, or adjective, by which its grammatical case, number, and gender are identified. b the class in which a noun etc. is put according to the exact form of this variation. 2 deterioration, declining. Derivatives declensional adj. Etymology: OF declinaison f. decliner DECLINE after L declinatio: assim. to ASCENSION etc. DECLINATION n. 1 a downward bend or turn. 2 Astron. the angular distance of a star etc. north or south of the celestial equator. 3 Physics the angular deviation of a compass needle from true north. 4 US a formal refusal. Derivatives declinational adj. Etymology: ME f. L declinatio (as DECLINE)