1.  impulse(n = noun.motive) urge - an instinctive motive; "profound religious impulses"
is a kind of motivation, motive, need
has particulars: abience, adience, death instinct, death wish, thanatos, itchy feet, wanderlust

2.  impulse(n = noun.feeling) caprice, whim - a sudden desire; "he bought it on an impulse"
is a kind of desire

3.  impulse(n = noun.event) nerve impulse, nervous impulse, neural impulse - the electrical discharge that travels along a nerve fiber; "they demonstrated the transmission of impulses from the cortex to the hypothalamus"
is a kind of electrical discharge
has particulars: action potential

4.  impulse(n = noun.event) pulsation, pulse, pulsing - (electronics) a sharp transient wave in the normal electrical state (or a series of such transients); "the pulsations seemed to be coming from a star"
is a kind of undulation, wave

5.  impulse(n = noun.act) impetus, impulsion - the act of applying force suddenly; "the impulse knocked him over"
is a kind of drive, driving force, thrust

6.  impulse(n = noun.attribute) momentum - an impelling force or strength; "the car's momentum carried it off the road"
is a kind of force, forcefulness, strength

1.  The act of impelling, or driving onward with sudden force; impulsion; especially, force so communicated as to produced motion suddenly, or immediately. [1913 Webster]
"All spontaneous animal motion is performed by mechanical impulse." [1913 Webster]

2.  The effect of an impelling force; motion produced by a sudden or momentary force. [1913 Webster]

3.  The action of a force during a very small interval of time; the effect of such action; as, the impulse of a sudden blow upon a hard elastic body. [1913 Webster]

4.  A mental force which simply and directly urges to action; hasty inclination; sudden motive; momentary or transient influence of appetite or passion; propension; incitement; as, a man of good impulses; passion often gives a violent impulse to the will; to buy something on impulse. [1913 Webster]
"These were my natural impulses for the undertaking."

   To impel; to incite. Pope. [1913 Webster]

impulse, n.
1 the act or an instance of impelling; a push.
2 an impetus.
3 Physics a an indefinitely large force acting for a very short time but producing a finite change of momentum (e.g. the blow of a hammer). b the change of momentum produced by this or any force.
4 a wave of excitation in a nerve.
5 mental incitement.
6 a sudden desire or tendency to act without reflection (did it on impulse).

Idiom:
impulse buying the unpremeditated buying of goods as a result of a whim or impulse.

Etymology:
L impulsus (as IMPEL)

N  impulse, sudden thought, impromptu, improvisation, inspiration, flash, spurt, improvisatore, creature of impulse, extemporaneous, impulsive, indeliberate, snap, improvised, improvisate, improvisatory, unpremeditated, unmeditated, improvise, unprompted, unguided, natural, unguarded, spontaneous, instinctive, extempore, extemporaneously, offhand, impromptu, a limproviste, improviso, on the spur of the moment, on the spur of the occasion, impulse, impulsion, impetus, momentum, push, pulsion, thrust, shove, jog, jolt, brunt, booming, boost, throw, explosion, propulsion, percussion, concussion, collision, occursion, clash, encounter, cannon, carambole, appulse, shock, crash, bump, impact, elan, charge, beating, blow, dint, stroke, knock, tap, rap, slap, smack, pat, dab, fillip, slam, bang, hit, whack, thwack, cuff, squash, dowse, swap, whap, punch, thump, pelt, kick, punce, calcitration, ruade, arietation, cut, thrust, lunge, yerk, carom, carrom, clip, jab, plug, sidewinder, sidewipe, sideswipe, hammer, sledge hammer, mall, maul, mallet, flail, ram, rammer, battering ram, monkey, pile-driving engine, punch, bat, cant hook, cudgel, ax, dynamics, seismometer, accelerometer, earthquake detector, impelling, impulsive, impellent, booming, dynamic, dynamical, impelled, a hit, a very palpable hit, impulse, sudden thought, impromptu, improvisation, inspiration, flash, spurt, improvisatore, creature of impulse, extemporaneous, impulsive, indeliberate, snap, improvised, improvisate, improvisatory, unpremeditated, unmeditated, improvise, unprompted, unguided, natural, unguarded, spontaneous, instinctive, extempore, extemporaneously, offhand, impromptu, a limproviste, improviso, on the spur of the moment, on the spur of the occasion, impulse, impulsion, impetus, momentum, push, pulsion, thrust, shove, jog, jolt, brunt, booming, boost, throw, explosion, propulsion, percussion, concussion, collision, occursion, clash, encounter, cannon, carambole, appulse, shock, crash, bump, impact, elan, charge, beating, blow, dint, stroke, knock, tap, rap, slap, smack, pat, dab, fillip, slam, bang, hit, whack, thwack, cuff, squash, dowse, swap, whap, punch, thump, pelt, kick, punce, calcitration, ruade, arietation, cut, thrust, lunge, yerk, carom, carrom, clip, jab, plug, sidewinder, sidewipe, sideswipe, hammer, sledge hammer, mall, maul, mallet, flail, ram, rammer, battering ram, monkey, pile-driving engine, punch, bat, cant hook, cudgel, ax, dynamics, seismometer, accelerometer, earthquake detector, impelling, impulsive, impellent, booming, dynamic, dynamical, impelled, a hit, a very palpable hit.

N  motive, springs of action, wellsprings of action, reason, ground, call, principle, by end, by purpose, mainspring, primum mobile, keystone, the why and the wherefore, pro and con, reason why, secret motive, arriere pensee, intention, inducement, consideration, attraction, loadstone, magnet, magnetism, magnetic force, allectation, allective, temptation, enticement, agacerie, allurement, witchery, bewitchment, bewitchery, charm, spell, fascination, blandishment, cajolery, seduction, seducement, honeyed words, voice of the tempter, song of the Sirens forbidden fruit, golden apple, persuasibility, persuasibleness, attractability, impressibility, susceptibility, softness, persuasiveness, attractiveness, tantalization, influence, prompting, dictate, instance, impulse, impulsion, incitement, incitation, press, instigation, provocation, inspiration, persuasion, suasion, encouragement, advocacy, exhortation, advice, solicitation, lobbyism, pull, incentive, stimulus, spur, fillip, whip, goad, ankus, rowel, provocative, whet, dram, bribe, lure, decoy, decoy duck, bait, trail of a red herring, bribery and corruption, sop, sop for Cerberus, prompter, tempter, seducer, seductor, instigator, firebrand, incendiary, Siren, Circe, agent provocateur, lobbyist, impulsive, motive, suasive, suasory, persuasive, persuasory, hortative, hortatory, protreptical, inviting, tempting suasive, suasory, seductive, attractive, fascinating, provocative, induced, disposed, persuadable, spellbound, instinct with, smitten with, infatuated, inspired, by, because, therefore, from this motive, from that motive, for this reason, for that reason, for, by reason of, for the sake of, count of, out of, from, as, forasmuch as, for all the world, on principle, fax mentis incendium gloriae, temptation hath a music for all ears, to beguile many and be beguiled by one.

blind impulse, impulse explosive, impulse turbine, irrational impulse, irresistible impulse, nerve impulse