impetus

UK: /ˈɪmpɪtəs/ US: /ˈɪmpɪtəs/ ,(im′pi təs)

Inflections of 'impetus' (n): npl: impetuses

WordReference Random House Learner's Dictionary of American English © 2026

im•pe•tus /ˈɪmpɪtəs/   n., pl. -tus•es. 

1. a force that moves one to action;
   impulse:
   [countable] Some children need an impetus to study.
2. Mechanics the momentum of a moving body:
   [uncountable] The sled zoomed downhill under its own impetus.

See -pet-.

WordReference Random House Unabridged Dictionary of American English © 2026

im•pe•tus  (im′pi təs), n., pl. -tus•es. 

1. a moving force;
   impulse;
   stimulus:
   The grant for building the opera house gave impetus to the city's cultural life.
2. Mechanics (broadly) the momentum of a moving body, esp. with reference to the cause of motion.

• Latin: an attack, literally, a rushing into, perh. by haplology from *impetitus (though the expected form would be *impetītus; see appetite), equivalent. to impetī-, variant stem of impetere to attack (im- im-¹ + petere to make for, assault) + -tus suffix of verb, verbal action
• 1650–60

Synonyms

• 1. stimulation, spur, boost.

Collins Concise English Dictionary © HarperCollins Publishers::

impetus / ˈɪmpɪtəs/ noun ( -tuses)

1. an impelling movement or force; incentive or impulse; stimulus
2. the force that sets a body in motion or that tends to resist changes in a body's motion

Etymology: 17th Century: from Latin: attack, from impetere to assail, from im- (in) + petere to make for, seek out