a geometric line, curve, plane, or curved surface that touches another curve or surface at one point but does not intersect it
2.
tan (of an angle) a trigonometric function that in a right-angled triangle is the ratio of the length of the opposite side to that of the adjacent side; the ratio of sine to cosine
3.
the straight part on a survey line between curves
4.
music a part of the action of a clavichord consisting of a small piece of metal that strikes the string to produce a note
5.
on a tangent, at a tangent on a completely different or divergent course, esp of thought: to go off at a tangent
—adj
6.
a. of or involving a tangent
b. touching at a single point
7.
touching
8.
almost irrelevant
[C16: from Latin phrase līnea tangēns the touching line, from tangere to touch]