n.

1. 推動，促進；推動力；刺激[U][S1][（+to）][+to-v]
   The president's plan gave fresh impetus to industry.

   總統的計畫進一步推動了工業的發展。

2. 衝力[U]
   The car ran down the hill under its own impetus.

   汽車藉著本身的衝力滑下山。

n.