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impetus

/ˈɪmpɪtəs//ˈɪmpɪtəs/·noun
a force or stimulus that drives something forward or sets it moving
Fig. 1 — I watch a single rocket on a launch pad, its fuse cold, going nowhere.
01Definition

An impetus is the push that gets something going or keeps it moving. A new law can give impetus to clean energy; a crisis can be the impetus for reform. The word comes from the Latin for 'attack, impulse', and it keeps that sense of a driving force applied at the right moment — the shove that turns intention into motion. Once enough impetus is behind a movement, it can carry forward under its own weight.

02In use
  • iThe discovery gave fresh impetus to a field that had stalled for nearly a decade.
  • iiPublic anger over the scandal became the impetus, the catalyst that finally forced new rules.
  • iiiRising fuel prices provided both the impetus and the momentum for cities to expand public transit.
03Collocations
  • give impetus to
  • provide the impetus
  • fresh impetus
  • the impetus for change
  • gather impetus

Family impetuous (adjective)

04Relations

=stimulus, impulse, drive, motivation, momentum

≠hindrance, obstacle

05Compared
PairThe difference
impetus vs catalystthe agent that causes change and survives it unchanged → catalyst; the force transferred into something to move it, and spent → impetus.
impetus vs momentumthe push that starts the motion → impetus; the force that keeps it going → momentum.
06TOEFL & IELTS

A favorite of IELTS Writing Task 2 on change and development: 'give impetus to', 'provide the impetus for'. It is an uncountable noun used with give/provide/gain. Don't confuse it with the related adjective 'impetuous' (acting rashly on impulse). Stress falls on the first syllable: IM-pe-tus.

07Asked
How do you pronounce impetus?
IM-pe-tus — three syllables, stress firmly on the first. The common slip is putting the stress on the middle ('im-PET-us'), by false analogy with words like 'petition'; resist it. The i is short, as in 'imp'. The related adjective impetuous shifts everything: im-PET-choo-us, stress on the second syllable.
What is the plural of impetus?
Impetuses — the regular English -es ending. The Latin look of the word tempts people toward 'impeti', but that is wrong; impetus did not take a standard Latin plural, so English simply adds -es. In practice the plural is rare, because impetus is usually uncountable ('give impetus to'), used with give, provide, or gain.
What does 'give impetus to' mean?
To provide the push that gets something moving or moving faster — 'the discovery gave impetus to the research'. Impetus is uncountable here, and its verbs are give, provide, add, and gain. The scene above is the sense in one image: a cold rocket on the pad, and the single spark that ignites the fuse and lifts it off.
What is the difference between impetus and impetuous?
Different parts of speech from the same root. Impetus is a noun — a driving force ('the impetus for change'). Impetuous is an adjective describing a person who acts rashly, on sudden impulse ('an impetuous decision'). One is the push; the other is being too easily pushed. The -ous ending marks the adjective.
What does impetus mean in physics?
In an old, pre-Newtonian theory, impetus was an inner force imagined to keep a moving object going after the initial push — a medieval attempt to explain motion that Newton's momentum and inertia later replaced. The everyday word still carries a trace of it: impetus is the force that sets a thing going and, for a while, keeps it going.
What is the difference between impetus and momentum?
The quick tell: impetus is the push that starts or drives something, while momentum is the built-up motion that keeps it going once started. The full contrast, with both animated scenes, is on the impetus vs momentum page in the 'Compared' list above.