Origins
An impulse is the mind being shoved.βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ The word comes from Latin impulsus, the past participle of impellere β 'to push into' or 'to drive against', from in- ('into') + pellere ('to push').
The Latin pellere is one of the most prolific roots in English, and every descendant preserves the core meaning of pushing, just in a different direction. Compel pushes together (forcing). Expel pushes out (ejecting). Propel pushes forward (driving). Repel pushes back (rejecting). Dispel pushes apart (scattering). Appeal pushes toward (a judge). Pulse is a rhythmic push β the heart driving blood through the body.
The physical meaning of impulse came first. In mechanics, an impulse is a force acting briefly β a shove rather than a sustained pressure. Newton used the term in this precise sense. The psychological meaning β a sudden urge to act β developed from the metaphor of the mind being struck or pushed before rational thought can intervene.
Proto-Indo-European Roots
The Proto-Indo-European root *pel- meant 'to push' or 'to strike', and it branched widely. Through Germanic it may connect to felt (wool pushed and pressed together). Through Greek, it connects to polemics (the clash of pushed arguments).
Modern usage has given impulse a consumer dimension. 'Impulse buying' β purchasing without forethought β was first documented in marketing research in the 1940s, but the Latin metaphor holds perfectly: the shopper is pushed into action before deliberation can resist.