"heavy hammer," Old English slecg "hammer, mallet," from Proto-Germanic *slagjo- (cf. Old Norse sleggja, Middle Swedish sleggia "sledgehammer"), related to slege "beating, blow, stroke" and slean "to strike" (see slay (v.)). Sledgehammer is pleonastic.
"sleigh," 1610s, from dialectal Dutch sleedse, variant of slede (see sled (n.)); said by OED to be perhaps of Frisian origin.
any freight- or passenger-carrying device that is dragged or pushed without the aid of wheels. The travois of the North American Indian was a sledge consisting of two transversely connected wooden shafts dragged at an angle to the ground. Sledges date back to antiquity; Assyrian and Egyptian reliefs depict huge statues being pulled by sledge. The arrival of the wheel and axle ended the use of the sledge except in its snow-and-ice surface form of sled-a body mounted on runners. See also litter