Etymology
The origin of the verb is unknown, but it has possibly been influenced by the surname Scrimshaw. Various etymologies have been proposed (for example, that it derives from scrimshank (“(Britain, military slang) to be idle, to shirk duty”)), but the Oxford English Dictionary does not consider any of them convincing. Following the surname theory, Etymonline ultimately derives the word probably from Old French escremisseor (“fencing-master”).
The noun is probably derived from the verb.