Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., "in a raw state," from Latin crudus "rough; not cooked, raw, bloody," from PIE *krue-do-, from PIE *kreue- (1) "raw flesh" (see raw). Meaning "lacking grace" is first attested 1640s. Related: Crudely; crudeness. Crude oil is from 1865.