tangenttan•gent /'tændʒ(ə)nt/

n C

1. 【数】非正式 正切；切线；切面

2. 离题

词组go (或fly) off at a tangent 离题；行为(或思想)忽然改变

• Then he went off at a tangent to talk about his travels around the world. 然后他突然离题谈起他周游世界之事。