scalp: [13] Scalp originally meant ‘top of the head, cranium’; it was not used for the ‘skin on top of the head’ until the 17th century. It is not altogether clear where the word came from, but its resemblance to Old Norse skálpr ‘sheath, shell’ and the fact that it first appeared in Scotland and the north of England suggest that it was borrowed from a Scandinavian language. Its ultimate ancestor was no doubt the Germanic base *skal-, *skel-, *skul-, source also of English shell and probably skull. => scale, shell, skull
scalp (n.)
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 the source of scale (n.1). 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.
scalp (v.)
"to cut off (someone's) scalp," 1670s, from scalp (n.), originally in reference to North American Indians. For ticket re-selling sense, see scalper. Related: Scalped; scalping. Compare German skalpern, Danish skalpere, Swedish skalpera. French scalper is from Germanic. Similarity to Latin scalpere "to cut, carve" is accidental.