The Collaborative International Dictionary of English v.0.48:

Kilowatt \Kil"o*watt\, n. [See Kilogram and Watt.] (Elec.)
   One thousand watts.
   [1913 Webster]

WordNet (r) 3.0 (2006):

kilowatt
    n 1: a unit of power equal to 1000 watts [syn: kilowatt, kW]