Source : Webster's Revised Unabridged Dictionary (1913)

Splashboard \Splash"board`\, n.
   A guard in the front part of vehicle, to prevent splashing by
   a mud or water from the horse's heels; -- in the United
   States commonly called dashboard.

Source : WordNet®

splashboard
     n 1: protective covering consisting of a broad plank along a
          gunwale to keep water from splashing over the side [syn:
           {washboard}]
     2: protective covering consisting of a panel to protect people
        from the splashing water or mud etc. [syn: {splasher}, {dashboard}]