Source : Webster's Revised Unabridged Dictionary (1913)

Overheat \O`ver*heat"\, v. t. [Cf. {Superheat}.]
   To heat to excess; to superheat. --Cowper.

Source : WordNet®

overheat
     v 1: get excessively and undesirably hot; "The car engines
          overheated"
     2: make excessively or undesirably hot; "The room was
        overheated"