The Collaborative International Dictionary of English v.0.48:
Economizer \E*con"o*mi`zer\, n. 1. One who, or that which, economizes. [1913 Webster] 2. Specifically: (Steam Boilers) An arrangement of pipes for heating feed water by waste heat in the gases passing to the chimney. [1913 Webster]WordNet (r) 3.0 (2006):
economizer n 1: a frugal person who limits spending and avoids waste [syn: economizer, economiser]