Source : Webster's Revised Unabridged Dictionary (1913)

Deadbeat \Dead"beat`\, a. (Physics)
   Making a beat without recoil; giving indications by a single
   beat or excursion; -- said of galvanometers and other
   instruments in which the needle or index moves to the extent
   of its deflection and stops with little or no further
   oscillation.

   {Deadbeat escapement}. See under {Escapement}.