Tangency n. : The quality or state of being tangent; a contact or touching.

Example:
How do you find a point of Tangency given a circle's equation and a point on the tangent?

Taxonomy
tangent, tangent line, curve, graph, slope, the origin, passing, derivatives, tangent function, straight line, difference quotient, tangent plane, vertex, point of tangency, touches, slope formula, graph of a function, free encyclopedia.

Defination from the web:
tangency, the tangent line is "going in the same direction" as the curve, and in this sense it is the best ... tangent to a curve does not cross the curve at the point of tangency (though it may, when continued, cross the curve at other places away from ...