Definition of: tangent

(tan′jənt) adjective
1. Geom. Meeting at a point or along a line without further coincidence or intersection: said of either or both of two lines or surfaces so touching.
2. Touching; in contact.
—noun
1. Geom. a A line tangent to a curve at any point, b The straight line through two coincident points of a curve. c The length of a tangent line from the point of contact to the axis of abscissas.
2. Trig. One of the functions of an angle; the quotient of the ordinate divided by the abscissa.
3. A sharp change in course or direction.
—to fly (or go) off on a tangent Colloq. To make a sharp or sudden change in direction or course of action. [<L tangens, -entis, ppr. of tangere touch]