tangent

noun

1. A straight line touching a curve at a single point without crossing it there.

   “One feature of the body, which is constructed of pressed-steel members, is the contour of the sides. They are in the form of a continuous radius from the bottom side to the cant rail, and to enable flat glass windows to be fitted the side panels are pressed around the window opening, forming a tangent to the curved bodyside.”

2. A function of an angle that gives the ratio of the sine to the cosine, in either the real or complex numbers. Symbols: tan, tg.
3. A topic nearly unrelated to the main topic, but having a point in common with it.

   “I believe we went off onto a tangent when we started talking about monkeys on unicycles at his retirement party.”

   ““Uncle Barnaby was always father and mother to me,” Benson broke in; then after a pause his mind flew off at a tangent. “Is old Hannah all right—in the will, I mean?””

   “Jon & Kate Plus 8 is a show based on two facts: (1) Jon and Kate Gosselin have eight children, and (2) the word ‘Kate’ rhymes with the word ‘eight’. One suspects that if Kate were ever to have another child, a shady network executive would urge her to put it in a binbag with a brick and drop it down a well. But this is just a horrifying tangent.”

4. A visual interaction between two or more lines or edges that creates a perceived relationship between them, often in a way that the artist did not intend.
5. A small metal blade in a clavichord that strikes the strings to produce sound.

adj

1. (not-comparable)Touching a curve at a single point but not crossing it at that point.
2. (not-comparable)Of a topic, only loosely related to a main topic.
3. (not-comparable)Straight; not horizontally curved.

   “The collision occurred on a two-mile stretch of tangent track.”