də̇ˈklenchən, dēˈ- noun
( -s )
Etymology: probably alteration (influenced by -ion ) of earlier declenson, modification of Middle French declinaison grammatical declension, grammatical inflection, decline, from Late Latin declination-, declinatio grammatical declension (from Latin, grammatical inflection) & Latin declination-, declinatio grammatical inflection, avoidance, turning aside, from Latin declinatus (past participle of declinare to inflect grammatically, turn aside) + -ion-, -io -ion — more at decline
1.
a. : noun, adjective, or pronoun inflection
b. : a presentation in some prescribed order of the inflectional forms of a noun, adjective, or pronoun
c. : a class of nouns or adjectives having the same type of inflectional forms
Latin nouns of the second declension have their nominative singular in -us or -um and their genitive singular in -ī
Latin adjectives of the third declension such as facilis
2. : a falling off or away especially from a standard or a high point of development : decline
seems to mark a declension in his career as an illustrator — F.J.Mather
: deterioration
makes me wish to reflect, … to see if it is all loss, all declension — A.C.Benson
3. : a bending or sloping downward : descent
the declension of the land from that place to the sea — Thomas Burnet
4. : a courteous refusal : declination
his declension of the nomination