early 14c., "to show signs of madness or delirium," from Old French raver, variant of resver "to dream; wander here and there, prowl; behave madly, be crazy," of unknown origin (compare reverie). The identical (in form) verb meaning "to wander, stray, rove" first appeared c. 1300 in Scottish and northern dialect, and is probably from an unrelated Scandinavian word (such as Icelandic rafa). Sense of "talk enthusiastically about" first recorded 1704. Related: Raved; raving.
"act of raving," 1590s, from rave (v.). Meaning "temporary popular enthusiasm" is from 1902; that of "highly flattering review" is from 1926. Sense of "rowdy party" is from 1960; rave-up was British slang for "wild party" from 1940; specific modern sense of "mass party with loud, fast electronic music and often psychedelic drugs" is from 1989.