Tangent  n. 1 (often attrib.) Straight line, curve, or surface that meets a curve at a point, but does not intersect it. 2 ratio of two sides (other than the hypotenuse) opposite and adjacent to an acute angle in a right-angled triangle.  at a tangent diverging from a previous course or from what is relevant or central (go off at a tangent). [latin tango tact- touch]