The Collaborative International Dictionary of English v.0.48:
Excavator \Ex"ca*va`tor\, n. One who, or that which, excavates or hollows out; a machine, as a dredging machine, or a tool, for excavating. [1913 Webster]WordNet (r) 3.0 (2006):
excavator n 1: a workman who excavates for foundations of buildings or for quarrying 2: a machine for excavating [syn: power shovel, excavator, digger, shovel]