Is it ensure, insure, or assure?
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 (cf. 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 (cf. 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.
: rave noticesnoun
To commend or applaud enthusiastically: He's raving over this new book (1816+)Related Terms
[rave meant ''party'' in British slang by 1960]
[WPI] 1. To persist in discussing a specific subject.
2. To speak authoritatively on a subject about which one knows very little.
3. To complain to a person who is not in a position to correct the difficulty.
4. To purposely annoy another person verbally.
5. To evangelise. See flame.
6. Also used to describe a less negative form of blather, such as friendly bullshitting. "Rave" differs slightly from flame in that "rave" implies that it is the persistence or obliviousness of the person speaking that is annoying, while flame implies somewhat more strongly that the tone or content is offensive as well.