impulse

n. [ L. impulsus, fr. impellere. See Impel. ] [ 1913 Webster ]

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. S. Clarke. [ 1913 Webster ]

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

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. [ 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 +PJC ]

These were my natural impulses for the undertaking. Dryden.

Syn. -- Force; incentive; influence; motive; feeling; incitement; instigation. [ 1913 Webster ]