From Middle English sleen, slayn, from Old English slēan ("to strike, beat, smite, stamp, forge, sting, slay, kill, impact"), from Proto-West Germanic *slahan, from Proto-Germanic *slahaną ("to fight, strike, kill"), from Proto-Indo-European *slak- ("to hit, strike, throw").
Cognate with Dutch slaan ("to beat, hit, strike"), Low German slaan ("hit, strike"), German schlagen ("to beat, hit, strike"), Danish, Norwegian and Swedish slå ("to knock, beat, strike"), Icelandic slá ("to strike"). Related to slaughter, onslaught.