mid-14c., "top of the head (including hair)," presumably from a Scandinavian source (though exact cognates are wanting) related to Old Norse skalli "a bald head," skalpr "sheath, scabbard," from PIE root *skel- (1) "to cut." French scalpe, German, Danish, Swedish skalp are from English. Meaning "head skin and hair as proof of death or a victory trophy" is from c. 1600.