1
- a straight line or plane that touches a curve or curved surface at a point, but if extended does not cross it at that point切线, 切面。
1.1
- figurative a completely different line of thought or action〈喻〉完全不相干的想法或举动; 离题：
Loretta's mind went off at a tangent.
洛蕾塔的思想突然离题了。
2
- Mathematics the trigonometric function that is equal to the ratio of the sides (other than the hypotenuse) opposite and adjacent to an angle in a right-angled triangle【数】正切。
- (of a line or plane) touching, but not intersecting, a curve or curved surface（线, 平面）正切的。
派生词
tangency
noun词源
late 16th cent. (in sense 2 and as an adjective)： from Latin tangent- 'touching'， from the verb tangere.