Source : Webster's Revised Unabridged Dictionary (1913)

Impact \Im"pact\, n.
   1. Contact or impression by touch; collision; forcible
      contact; force communicated.

            The quarrel, by that impact driven.   --Southey.

   2. (Mech.) The single instantaneous stroke of a body in
      motion against another either in motion or at rest.

Impact \Im*pact"\, v. t. [imp. & p. p. {Impacted}; p. pr. & vb.
   n. {Impacting}.] [L. impactus, p. p. of impingere to push,
   strike against. See {Impinge}.]
   To drive close; to press firmly together: to wedge into a
   place. --Woodward.

Source : WordNet®

impact
     n 1: the striking of one body against another
     2: a forceful consequence; a strong effect; "the book had an
        important impact on my thinking"; "the book packs a
        wallop" [syn: {wallop}]
     3: influencing strongly; "they resented the impingement of
        American values on European culture" [syn: {impingement},
        {encroachment}]
     4: the violent interaction of individuals or groups entering
        into combat; "the armies met in the shock of battle" [syn:
         {shock}]

impact
     v 1: press or wedge together; pack together
     2: have an effect upon; "Will the new rules affect me?" [syn: {affect},
         {bear upon}, {bear on}, {touch on}, {touch}]