Green’s Dictionary of Slang

1. whatever happens, at all events.

1900		A.H. Lewis ‘Short Creek Dave’ in Sandburrs 72: ‘That’s whatever!’ agreed Dan Boggs.
1910		P.W. Joyce Eng. As We Speak It In Ireland.
1999		K. Sampson Powder 47: Guy doubted the relationship would stand too much strain. Whatever. So be it.
2000		T. Blacker Kill Your Darlings 90: He laughed. ‘Whatever.’.

2. (orig. US black/teen, also wevs, whatevers, whatevs, wotevs) a general expression of dismissal, disinterest.

1965		R. Baer Bewitched [TV script] (2nd Ser. Episode 1) Endora: Good Morning, Derwood. Samantha Stephens: Darrin. Endora:... Whatever.
1970		Current Sl. IV:2 10: Whatever’s fair. Yes; no (as an evasive reply to a direct question).
1977		(con. 1969) M. Herr Dispatches 130: ‘It gets me outta the Corps three months early.’ ‘Whatever, Jim.’.
1989		P. Munro Sl. U. 204: whatever I don’t care. That’s weird. Have it your way. I don’t want to argue.
1995		A. Heckerling Clueless [film script] summer: Hey, Cher! Is it true some gang members, like tried to shoot Tai in the mall? cher: No. summer: That is what everyone is saying. cher: Whatever.
1999		R.G. Barrett Wind & Monkey (2013) [ebook] ‘Whatever,’ replied agent Corris.
2005		P. Howard Curious Incident of the Dog in the Nightdress 35: Hey, did you hear I’m actually coaching [...] and she just goes, ‘Whatever!’.
2010		L. Berney Gutshot Straight [ebook] ‘Where are we going?’ she asked. ‘You’ll see.’ ‘Whatevers’.
2012		M. Lacher On the Bro’d 14: [A][ bunch of not-hot bitches who were talking about some bullshit conference — bitch-bitch, whatever-whatever [ibid.] 15: I figured whatevs.
2016		Independent 5 Jan. 🌐 Homegrown expressions reflect teen habits of overstating: devs or devo’d for devastated (mildly inconvenienced); and feigning indifference—wotevs or whevs. CBA or ceebs (short for ‘can’t be arsed’) .