Impulse, n.
Etymology: [L. impulsus, fr. impellere. See Impel.]
1. The act of impelling, or driving onward with sudden force; impulsion; especially, force so communicated as to produced motion suddenly, or immediately. All spontaneous animal motion is performed by mechanical impulse. S. Clarke.
2. The effect of an impelling force; motion produced by a sudden or momentary force.
3. (Mech.)
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.
2 more senses
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. These were my natural impulses for the undertaking. Dryden.
Syn. -- Force; incentive; influence; motive; feeling; incitement; instigation.
1 other Webster entry under this spelling
Impulse, v. t.
To impel; to incite. [Obs.] Pope.
Shades of meaning
Fernald has no entry of its own for impulse; he lists it under appetite.
He lists it without comment; the entries above explain its neighbors.