Tangential \Tan*gen"tial\, a. (Geom.) Of or pertaining to a tangent; in the direction of a tangent.

Tangential force (Mech.), a force which acts on a moving body in the direction of a tangent to the path of the body, its effect being to increase or diminish the velocity; -- distinguished from a normal force, which acts at right angles to the tangent and changes the direction of the motion without changing the velocity.

Tangential stress. (Engin.) See Shear, n., 3.

Source: Webster's Revised Unabridged Dictionary (1913)