a moving force; impulse; stimulus: The grant for building the opera house gave impetus to the city's cultural life.
(broadly) the momentum of a moving body, especially with reference to the cause of motion.
Origin of impetus
First recorded in 1650–60; from Latin: “an attack,” literally, “a rushing into,” perhaps by haplology from unattested impetitus (though the expected form would be unattested impetītus; see appetite), equivalent to impetī-, variant stem of impetere “to attack” (im-im-1 + petere “to make for, assault”) + -tus suffix of verb action
Finding someone to carry on the legacy of the DVF brand was part of the impetus behind her forthcoming E!
Diane von Furstenberg: How I Learned to Love My Wrap Dress|Lizzie Crocker|October 27, 2014|DAILY BEAST
My friend, Eleanor, who actually was also the impetus for my writing Running on Empty, was not a Very Good Girl.
Jamie Lee Curtis and Naomi Foner on What It Means to Be ‘Very Good Girls’|Jamie Lee Curtis|July 25, 2014|DAILY BEAST
These candidates all claimed that God was the impetus and continuing force behind their campaigns.
Judging by the GOP, God Can’t Pick a Campaign Winner|Brandy Zadrozny|June 3, 2014|DAILY BEAST
The impetus behind this decision was a desire to change the odds for children like my cousin and me.
There’s No Better Test for Millennials than the American City|Michael Tubbs|April 19, 2014|DAILY BEAST
The Arizona law seems to apply to services beyond those tied to weddings, but same-sex weddings are the impetus for these bills.
Conservative Christians Selectively Apply Biblical Teachings in the Same-Sex Marriage Debate|Kirsten Powers, Jonathan Merritt|February 23, 2014|DAILY BEAST
Entering between the shoulder and blade-bone, it is buried, by the victim's own impetus, to the very hilt.
Blackwood's Edinburgh Magazine, Volume 71, No. 436, February 1852|Various
At all events, the slope was so steep that the guide shot down it with an impetus sufficient to carry him clear over the schrund.
Hours of Exercise in the Alps|John Tyndall
Big-foot Sanders and Tad Butler, nearly half a mile ahead, felt the impetus, too.
The Pony Rider Boys in Texas|Frank Gee Patchin
You notice the river makes a sharp curve, and naturally enough the impetus of the water spread it over a wide territory.
The Johnstown Horror|James Herbert Walker
With his own development Rodin has given an impetus to all the arts in this confused age.
Auguste Rodin|Rainer Maria Rilke
British Dictionary definitions for impetus
impetus
/ (ˈɪmpɪtəs) /
nounplural-tuses
an impelling movement or force; incentive or impulse; stimulus
physicsthe force that sets a body in motion or that tends to resist changes in a body's motion
Word Origin for impetus
C17: from Latin: attack, from impetere to assail, from im- (in) + petere to make for, seek out