impetus
driving force or stimulus
Roots
- in- / im- (in/into): in, into, within, or on
- pet / petit: seek, aim at, rush toward, or attack
Other words with the pet / petit root
Impetus is the push that sends action forward.
One good quiz score gave him the impetus to keep studying.
Impetus and impetuous belong together. Impetus is the push; impetuous is what happens when the push outruns judgment.