1. (a.) Touching at a single point\.

2. (n.) A tangent line curve, or surface; specifically, that portion of the straight line tangent to a curve that is between the point of tangency and a given line, the given line being, for example, the axis of abscissas, or a radius of a circle produced. See Function.

3. (a.) 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.

abutter adjoiner air line approach asymptote axis beeline borderer bottleneck bystander chord collision course concentralization concentration concourse concurrence confluence conflux congress convergence converging crossing diagonal diameter direct line directrix edge focalization focus funnel great-circle course hub immediate neighbor looker-on meeting mutual approach narrowing gap neighbor neighborer normal onlooker perpendicular radius radius vector right line secant segment shortcut side spokes straight straight course straight line straight stretch straightaway streamline transversal vector