- (
geometry 几何 a straight line that touches the outside of a curve but does not cross it 切线 
The cart track branches off at a tangent. 大车轨道在切线处分叉。
- (abbreviation tan)(
mathematics 数学 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 正切
Word Originlate 16th cent. (in sense (2) and as an adjective): from Latin tangent- ‘touching’, from the verb tangere.
Idioms
fly/go off at a tangent (British English)
(North American English go off on a tangent)
- (informal)
to suddenly start saying or doing something that does not seem to be connected to what has gone before 突然转换话题；突然改变行动 He never sticks to the point but keeps going off at a tangent. 他从来不坚持要点，而是一直离题。 Laura’s mind went off at a tangent. 劳拉心不在焉。