noun

1. a bending or sloping downward; deviation from the horizontal or vertical
2. an oblique variation from some definite direction
3. the angle formed by a magnetic needle with the line pointing to the geographical North Pole
4. a polite declining or refusal
5. Archaic decline; deterioration; decay
6. Astron. the angular distance of a celestial body north or south from the celestial equator: it is used with right ascension to find an exact position in the sky: abbrev. Dec, dec

Etymology: ME declinacioun < L declinatio: see declension