impulse

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An impelling force; an impetus.
2. n. The motion produced by such a force.
3. n. A sudden wish or urge that prompts an unpremeditated act or feeling; an abrupt inclination: had an impulse to run away; an impulse of regret that made me hesitate; bought a hat on impulse.
4. n. A motivating force or tendency: "Respect for the liberty of others is not a natural impulse in most men” ( Bertrand Russell).
5. n. Electronics A surge of electrical power in one direction.
6. n. Physics The product obtained by multiplying the average value of a force by the time during which it acts. The impulse equals the change in momentum produced by the force in this time interval.
7. n. Physiology The electrochemical transmission of a signal along a nerve fiber that produces an excitatory or inhibitory response at a target tissue, such as a muscle or another nerve.
8. adj. Characterized by impulsiveness or acting on impulse: an impulse shopper; impulse buying.

Century Dictionary and Cyclopedia

1. n. Force communicated suddenly; the effect of an impelling force; a thrust; a push.
2. n. Specifically In mech.: An infinite force or action enduring for an infinitely short time, so as to produce a finite momentum. Strictly speaking, there is no such natural force; but mathematicians find it convenient to treat such actions as the blow of a hammer as if of this nature.
3. n. The resultant of all such forces acting on a body at any instant, resolved into a couple and a force along the axis of that couple.
4. n. The momentum produced by a force in any time.
5. n. A stimulation of the mind to action; the impelling force of appetite, desire, aversion, or other emotion; especially, a sudden disposition to perform some act which is not the result of reflection; sudden determination.
6. n. Any communication of force; any compelling action; instigation.
7. n. A mental impression; an idea.
8. n. Shock; onset.
9. To give an impulse to; incite; instigate.

Wiktionary

1. n. A thrust; a push; a sudden force that impels.
2. n. A wish or urge, particularly a sudden one prompting action.
3. n. physics The integral of force over time.
4. v. obsolete To impel; to incite.

GNU Webster's 1913

1. n. The act of impelling, or driving onward with sudden force; impulsion; especially, force so communicated as to produced motion suddenly, or immediately.
2. n. The effect of an impelling force; motion produced by a sudden or momentary force.
3. n. (Mech.) The action of a force during a very small interval of time; the effect of such action.
4. n. A mental force which simply and directly urges to action; hasty inclination; sudden motive; momentary or transient influence of appetite or passion; propension; incitement.
5. v. obsolete To impel; to incite.

WordNet 3.0

1. n. the electrical discharge that travels along a nerve fiber
2. n. an impelling force or strength
3. n. an instinctive motive
4. n. (electronics) a sharp transient wave in the normal electrical state (or a series of such transients)
5. n. the act of applying force suddenly
6. n. a sudden desire