impulse
/ˈɪmpʌls/noun
1
- a sudden strong and unreflective urge or desire to act冲动：
I had an almost irresistible impulse to giggle
我有一种几乎难以抗拒的冲动, 想要哈哈大笑
as modifier impulse buying.冲动购物。
1.1
- mass noun the tendency to act in this way冲动倾向：
he was a man of impulse, not premeditation.
他是个易冲动的人, 不事先多考虑。
2
- a driving or motivating force; an impetus推动力, 冲力：
an added impulse to this process of renewal.
对更新过程的又一推动力。
3
- a pulse of electrical energy; a brief current（电）脉冲：
nerve impulses
神经脉冲
a spiral is used to convert radio waves into electrical impulses.
一根螺线用来将无线电波转化成电脉冲。
4
- Physics a force acting briefly on a body and producing a finite change of momentum【物理】脉冲。
4.1
- a change of momentum so produced, equivalent to the average value of the force multiplied by the time during which it acts冲量。
短语
on impulse（或on an impulse）
- suddenly and without forethought; impulsively凭冲动, 冲动地。
词源
early 17th cent. （as a verb in the sense 'give an impulse to'）： the verb from Latin impuls- 'driven on'， the noun from impulsus 'impulsion， outward pressure'， both from the verb impellere （see IMPEL）.