Impetus refers to a force or impulse that causes something (such as a process or activity) to be done or to become more active. It is often used with for and sometimes with to.

// Her work provided the major impetus behind the movement.

// The tragic accident became an impetus for changing the safety regulations.

// The high salary and generous benefits package were impetus enough to apply for the job.

See the entry >

“... using the many tools now available, I built a family tree with over twelve hundred names of people living in some two dozen countries. If there is anything approaching a single story of humanity, it is surely one of movement, whatever the impetus.” — Diana McCaulay, LitHub.com, 27 Feb. 2025

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.