/ˈɪmpʌls ||; ˈɪmpʌls/noun[C] 1 [usu.sing] an impulse (to do sth) a sudden desire to do sth without thinking about the results 冲动；突如其来的念头: She felt a terrible impulse to rush out of the house and never come back. 突然间她心里有个冲动，恨不得冲出屋去，再也不回来。
2 (technical术语) a force or movement of energy that causes a reaction 电路脉冲；神经冲动: nerve/electrical impulses 神经冲动；脉冲
on (an) impulse without thinking or planning and not considering the results 一时冲动:
When I saw the child fall in the water, I just acted on impulse and jumped in after her. 看到那个孩子掉进水里，我就凭冲动行事，跟着跳进去。