impetus

noun

im·​pe·​tus ˈim-pə-təs 

1

a(1)

: a driving force : impulse

(2)

: incentive, stimulus

b

: stimulation or encouragement resulting in increased activity

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

Did you know?

Impetus Has Latin Roots

Impetus provides the “why” for something: it can be understood as a driving force (as when winning a competition is the impetus for training), an incentive (as when increased skills serve as an impetus for taking a class), or encouragement (as when difficulties are the impetus for improvements). But its root packs more of a wallop: Latin impetus means “assault” as well as “impetus,” and it comes from impetere meaning “to attack.” (Impetere itself comes from petere, meaning “to go to, seek.”) If these origins seem a tad aggressive for such a genteel-sounding word as impetus, consider phrases and idioms like light a fire under someone and push comes to shove, both used when a strong impetus is provided for someone to act, decide, or accomplish something.

Synonyms

• incentive
• encouragement
• motivation
• stimulus

Examples of impetus in a Sentence

In a revealing comment, Mr. Updike says an impetus for Rabbit, Run was the "threatening" success of Jack Kerouac's On the Road, the signature book of the 1950s Beat Generation, and its frenetic search for sensation. —Dennis Farney, Wall Street Journal, 16 Sept. 1992

But 1939 gave new impetus to the Western with the Cecil B. de Mille railway epic Union Pacific, John Ford's skillful and dramatic Stagecoach,  … and George Marshall's classic comic Western, Destry Rides Again. —Ira Konigsberg, The Complete Film Dictionary, 1987

… new techniques of navigation and shipbuilding enlarged trade and the geographical horizon; newly centralized power absorbed from the declining medieval communes was at the disposal of the monarchies and the growing nationalism of the past century gave it impetus … —Barbara W. Tuchman, The March of Folly, 1984

His discoveries have given impetus to further research.

the reward money should be sufficient impetus for someone to come forward with information about the robbery

Recent Examples on the Web

The impetus for the collaboration came from Smith’s own experience using garlic in her cooking. —Emily Burns, Footwear News, 28 Oct. 2025

Even further down the pyramid of impetus for his departure lay his recruiting. —Noah White, Miami Herald, 27 Oct. 2025

Part of the impetus for all these openings is the same reason Las Vegas is so primed for these restaurants in the first place. —Tori Latham, Robb Report, 19 Oct. 2025

And if Klopp felt the benefits of turning throw-ins into choreographed events, complete with long build-ups, would be outweighed in Liverpool’s case by a loss of attacking impetus, is there not something to be said for that? —Oliver Kay, New York Times, 16 Oct. 2025

Word History

Etymology

Latin, assault, impetus, from impetere to attack, from in- + petere to go to, seek — more at feather

First Known Use

1641, in the meaning defined at sense 1a(1)

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Kids Definition

impetus

noun

im·​pe·​tus ˈim-pət-əs 

1

a

: a driving force : impulse

b

: incentive

2

: momentum sense 1