The Collaborative International Dictionary of English v.0.48:

Impinge \Im*pinge"\, v. t. [imp. & p. p. Impinged; p. pr. &
   vb. n. Impinging.] [L. impingere; pref. im- in + pangere to
   fix, strike; prob. akin to pacisci to agree, contract. See
   Pact, and cf. Impact.]
   To fall or dash against; to touch upon; to strike; to hit; to
   clash with; -- with on or upon.
   [1913 Webster]

         The cause of reflection is not the impinging of light
         on the solid or impervious parts of bodies. --Sir I.
                                                  Newton.
   [1913 Webster]

         But, in the present order of things, not to be employed
         without impinging on God's justice.      --Bp.
                                                  Warburton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impinge
    v 1: impinge or infringe upon; "This impinges on my rights as an
         individual"; "This matter entrenches on other domains"
         [syn: impinge, encroach, entrench, trench]
    2: advance beyond the usual limit [syn: encroach, infringe,
       impinge]

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "impinge":
   bang, bang into, barge in, break in, break in upon, brush,
   brush by, bump, bump into, burst in, butt in, cannon, caress,
   carom, carom into, charge in, clash, collide, come between,
   come in contact, come into collision, concuss, confront each other,
   contact, crack up, crash, crash in, crash into, crash the gates,
   creep in, crowd in, crump, crunch, cut in, dash into, edge in,
   elbow in, encounter, encroach, entrench, fall foul of, foist in,
   foul, glance, graze, hit, hit against, horn in, hurt, hurtle,
   impose, impose on, impose upon, infiltrate, infringe, insinuate,
   interfere, interlope, interpose, intervene, intrude, invade,
   irrupt, kiss, knock, knock against, meet, nudge, obtrude, osculate,
   percuss, press in, push in, put on, put upon, rub, run into,
   rush in, scrape, shave, sideswipe, skim, skirt, slam into,
   slink in, slip in, smack into, smash, smash in, smash into,
   smash up, sneak in, squeak by, squeeze in, steal in, storm in,
   strike, strike against, throng in, thrust in, touch, trench,
   trespass, whomp, work in, worm in