1. A leaning; the act of bending down; as a declination of the head.
2. A declining, or falling into a worse state; change from a better to a worse condition; decay; deterioration; gradual failure or diminution of strength, soundness, vigor or excellence.
3. A deviation from a right line, in a literal sense; oblique motion; as the declination of a descending body.
4. Deviation from rectitude in behavior or morals; obliquity of conduct; as a declination from the path of integrity.
5. In astronomy, a variation from a fixed point or line. The distance of any celestial object from the equinoctial line, or equator, either northward or southward.
6. declination of the compass or needle, is the variation of the needle from the true meridian of a place.
7. In dialing, the declination of a wall or plane, is an arch of the horizon, contained between the plane and the prime vertical circle, if reckoned from the east or west, or between the meridian and the plane, if you reckon from the north or south.
8. In grammar, declension; or the inflection of a noun through its various terminations.