Source : Webster's Revised Unabridged Dictionary (1913)

Clash \Clash\, v. i. [imp. & p. p. {Clashed}; p. pr. & vb. n.
   {Clashing}.] [Of imitative origin; cf. G. klatschen, Prov. G.
   kleschen, D. kletsen, Dan. klaske, E. clack.]
   1. To make a noise by striking against something; to dash
      noisily together.

   2. To meet in opposition; to act in a contrary direction; to
      come onto collision; to interfere.

            However some of his interests might clash with those
            of the chief adjacent colony.         --Palfrey.

Source : WordNet®

clashing
     adj : sharply and harshly discordant; "clashing interests of
           loggers and conservationists"; "clashing colors"