Old English hamor "hammer," from Proto-Germanic *hamaraz (cf. Old Saxon hamur, Middle Dutch, Dutch hamer, Old High German hamar, German Hammer. The Old Norse cognate hamarr meant "stone, crag" (it's common in English place names), and suggests an original sense of "tool with a stone head," from PIE *akmen "stone, sharp stone used as a tool" (cf. Old Church Slavonic kamy, Russian kameni "stone"), from root *ak- "sharp" (see acme). Hammer and sickle as an emblem of Soviet communism attested from 1921, symbolizing industrial and agricultural labor.