1. The act of inclining, or state of being inclined; a leaning; as, an inclination of the head. 2. A direction or tendency from the true vertical or horizontal direction; as, the inclination of a column, or of a road bed. 3. A tendency towards another body or point 4. (Geom.) The angle made by two lines or planes; as, the inclination of the plane of the earth's equator to...