impetus n. [IM-puh-tus]
推动力，刺激；冲力
Definition
1 a: driving force : impulse
a：驱动力：冲动
b: incentive, stimulus
b：刺激，激励
c: stimulation or encouragement resulting in increased activity
c：导致进一步行为的刺激或激励
2 : the property possessed by a moving body in virtue of its mass and its motion - used of bodies moving suddenly or violently to indicate the origin and intensity of the motion.
【物】冲力；运动的物体由于其质量与运动而具有的一种属性 - 对于物体突然或者剧烈的运动，用于描述这种运动的起源与强度。
注：in virtue of：通过，由于
Did You Know?
You already have plenty of incentive to learn the origin of impetus, so we won't force the point. Impetus comes from Latin, where it means "attack or assault"; the verb impetere was formed by combining the prefix in- with petere, meaning "to go to or seek." Petere also gives us other words suggesting a forceful urging or momentum, such as appetite, perpetual, and centripetal. Impetus describes the kind of force that encourages an action ("the impetus behind the project") or the momentum of an action already begun ("the meetings only gave impetus to the rumors of a merger").
词源词根演化：in- + petere ("to go to or seek") --> impetere (v.) --> impetus (n. attack or assault)
你已经有很多激励来学习impetus的起源了，所以我们就不强调impetus作为“刺激，激励”这点了。impetus来自于拉丁词，当时的意思是“攻击或者突袭（目的是为了夺取）”； 拉丁动词impetere由前缀in-与petere（去或者寻）构成。petere也为我们贡献了其他的单词，暗含有强力地驱动或者强烈的动力，例如appetite（胃口），perpetual（永恒的）和centripetal（向心的）。impetus用于描述某种力量，使得 1）激发某种行为，例如the impetus behind the project (这个项目背后的驱动力) 或者 2）某种行为本身的动量，例如the mmetings only gave impetus to the rumors of a merge (这个会议更加激发了要做兼并重组的留言蜚语)
注：assault：攻击，突袭；urge：驱策，鼓励，催促，极力主张；momentum：势头，动力，【物】动量；perpetual：永久的，永恒的，一再往复的；centripetal：向心的
Examples
- The high salary and generous benefits package were impetus enough to apply for the job.
高薪高福利是申请这个职位的驱动力。
- "Several legislators who spoke at last week's workshop cited a recent series by the Post & Courier of Charleston as the impetus for this year's focus on education."
--- Kirk Brown, The Greenville (South Carolina) News, 9 Jan. 2019
在上周的工作会议上，不少立法委员都引用了Charleston的Post & Courier 的系列文章作为今年教育重点的背后驱动力。
注：the Post & Courier：一个新闻机构 The Post and Courier is the main daily newspaper in Charleston, South Carolina. It traces its ancestry to three newspapers, the Charleston Courier, founded in 1803, the Charleston Daily News, founded 1865, and The Evening Post, founded 1894.