Tangent Tan"gent, a. [L. tangens, -entis, p. pr.] Touching; touching at a single point; specifically (Geom.) meeting a curve or surface at a point and having at that point the same direction as the curve or surface; -- said of a straight line, curve, or surface; as, a line tangent to a curve; a curve tangent to a surface; tangent surfaces. [1913 Webster]

{Tangent plane} (Geom.), a plane which touches a surface in a point or line.

{Tangent scale} (Gun.), a kind of breech sight for a cannon.

{Tangent screw} (Mach.), an endless screw; a worm. [1913 Webster]

The Collaborative International Dictionary of English. 2000.