- 1(geometry) a straight line that touches the outside of a curve but does not cross it The cart track branches off at a tangent. See related entries: Mathematical terminology
- 2(abbreviation tan) (mathematics) the ratio of the length of the side opposite an angle in a right-angled triangle to the length of the side next to it compare cosine, sine See related entries: Mathematical terminology Word Origin late 16th cent. (in sense (2) and as an adjective): from Latin tangent-
(informal) to suddenly start saying or doing something that does not seem to be connected to what has gone before He never sticks to the point but keeps going off at a tangent. Laura’s mind went off at a tangent.