impulse

Etymology

Borrowed from Middle French impulser, from Latin impulsus. For spelling, as in pulse, the -e (on -lse) is so the end is pronounced /ls/, rather than /lz/ as in pulls, and does not change the vowel (‘u’). Compare else, false, convulse.

noun

1. A thrust; a push; a sudden force that impels.
   c. 1715-1716, Samuel Clarke, letter to Gottfried Wilhelm Leibniz All spontaneous animal motion is performed by mechanical impulse.
2. A wish or urge, particularly a sudden one prompting action.
   The impulse to learn drove me to study night and day.
   When I saw the new book, I couldn't resist the impulse to browse through it.
   Tony's face expressed relief, and Nettie sat silent for a moment until the vicar said “It was a generous impulse, but it may have been a momentary one,[…].” 1907, Harold Bindloss, chapter 20, in The Dust of Conflict
3. (physics) The integral of force over time.
   The total impulse from the impact will depend on the kinetic energy of the projectile.

verb

1. (transitive) To impel; to incite.