/ ˈtændʒənt; NAmE / noun
1.
( geometry ) a straight line that touches the outside of a curve but does not cross it
—picture at circle
2.
( abbr. tan ) ( mathematics ) the ratio of the length of the side opposite an angle in a right-angled triangle to the length of the side next to it
—compare cosine , sine
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IDIOMS
- fly / go off at a tangent
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WORD ORIGIN
late 16th cent. (in sense 2 and as an adjective): from Latin tangent- touching, from the verb tangere .