1. an eccentric, bizarre person.
|Goodbye to The Hill (1966) 81: I was a right head case, I know, but I cared about how much carboniferous limestone was in one country and how much rain fell annually in another.|
|Skin Tight 64: This broad is creepy, he thought, a real head case.|
|A Drink Before the War 25: Ann must have been dealing with a real headcase.|
|Soothing Music for Stray Cats 153: [I] found myself stuck [...] with my very own head-case.|
2. someone undergoing, or in need of, psychiatric treatment.
|Goodbye to The Hill (1966) 65: The next time we went for a drink he ordered whiskey on the rocks and I thought he was a head case until I saw the lumps of ice in his glass.|
|Book of Irish Soldiers’ Jokes 48: [Soldiers’ Alphabet] P for relief / Q for lunch / R for tea / S for you! You’re a head case.|
|Down and Out 160: He’s a nutter, a head case.|
|Indep. on Sun. 10 Oct. 11: If they took all the druggies and headcases out of Brixton, the place would be empty.|
|Emerald Germs of Ireland 305: A complete and utter bucking headcase!|
|Londonstani (2007) 167: Lots of hard cases were also head cases.|
3. a violent person, a psychotic.
|Long and the Short and the Tall Act I: You’re just a head case.|
|Cut and Run (1963) 88: Your man’s a bit o’ a head-case, eh?|
|Tucker and Co 9: They’d already had one brush with Gripper Stebson, now the unchallenged school headcase, and Jonah didn’t fancy the idea of another.|
|The Joy (2015) [ebook] He’s a bleedin headcase, with a love of knives and a lust for using them to cut people up, including himself.|
|Curvy Lovebox 116: Notice two of his Fan Club headcases laggin’ at the door.|
|Guardian Guide 12–18 Feb. 52: He’d only get done over [...] by some young thug or local headcase wanting to prove how hard he was.|
|Snitch Jacket 99: I began to grasp the appeal of a headcase like Charlie Manson.|
4. a state of psychosis.
|Nam (1982) 197: You did your duty, you didn’t run off to Canada. You didn’t fake some head case to go 4-F.|
5. a clever person, or one who believes themselves to be so.
|Happy Days Are Here Again (1968) 153: Everybody is sick of you, Liphitz! [...] Your intellectual headcases are sick of you.|