declension
de.clen.sion \di-'klen-ch*n\ \-'klench-n*l, -'klen-ch*n-*l\ n [prob. alter. of earlier declenson, modif. of MF declinaison, fr. L]L declination-, declinatio, fr. L, grammatical inflection, turning aside, fr. declinatus, pp. of declinare to inflect, turn aside 1a: noun, adjective, or pronoun inflection esp. in some prescribed order of the forms 1b: a class of nouns or adjectives having the same type of inflectional for ms 2: a falling off or away : DETERIORATION 3: DESCENT, SLOPE - de.clen.sion.al aj
Webster's English Dictionary