Declension /(?)/

De·clen·sion

Declension

n.
  1. The act or the state of declining; declination; descent; slope.
    The declension of the land from that place to the sea.
    — T. Burnet.
  2. A falling off towards a worse state; a downward tendency; deterioration; decay; as, the declension of virtue, of science, of a state, etc.
    Seduced the pitch and height of all his thoughts To base declension.
  3. Act of courteously refusing; act of declining; a declinature; refusal; as, the declension of a nomination.
  4. Inflection of nouns, adjectives, etc., according to the grammatical cases. (Gram.)

Phrases & Compounds
Declension of the needle
declination of the needle.