sledge
n.
1
"heavy hammer," Old English slecg "hammer, mallet," from Proto-Germanic *slagjo- (cognates: Old Norse sleggja, Middle Swedish sleggia "sledgehammer"), related to slege "beating, blow, stroke" and slean "to strike" (see slay, v.). Sledgehammer is pleonastic.
2
"sleigh," 1610s, from dialectal Dutch sleedse, variant of slede (see sled, n.); said by OED to be perhaps of Frisian origin.