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):

impinging
    n 1: the physical coming together of two or more things;
         "contact with the pier scraped paint from the hull" [syn:
         contact, impinging, striking]