Green’s Dictionary of Slang

wash out v.

1. (orig. milit.) to remove, to cancel, to dismiss (e.g. from a course).

[UK]N&Q 12 Ser. IX 348: Wash Out (To). To cancel, suppress.
[UK](con. 1916) F. Manning Her Privates We (1986) 200: This overcoat business will have to be washed out.
[UK]Wodehouse Right Ho, Jeeves 224: Why not chuck the whole idea of hitching up with me? Wash it out altogether.
[US]I. Shulman Cry Tough! 94: His mother and father didn’t understand him [...] And now – Larry and Bull – had washed him out.
[US]E. Gilbert Vice Trap 51: I’d been in basic training [...] and I was through the next week, washed out.
[UK]‘Frank Richards’ Billy Bunter at Butlins 10: Too late to wash it out now, isn’t it, Greeney?
[US]G. Liddy Will 94: [T]heir lockers were opened and the snap-brim hats all were required to have were measured. The three [FBI] agents with the smallest hat sizes were washed out.

2. (US) to lose all one’s money, esp. from gambling.

[US]D. Runyon ‘The Snatching of Bookie Bob’ in Runyon on Broadway (1954) 121: We are washed out. We owe every bookmaker at the track.

3. to lose or spoil anything.

[US]E.W. Calder ‘Black 13’ in Spicy Adventure Stories Aug. 🌐 You were a pilot on the Trans-American Air Lines. You washed out your ship over the desert.
[US]C.R. Bond 31 Dec. in A Flying Tiger’s Diary (1984) 69: He is okay but washed out his landing gear.

4. (US) to die, to be killed.

[US]E.C. Parsons Great Adventure 183: He was in a bad spot to defend himself [but] he had ideas that were decidedly averse to getting washed out .
[US]R. Woodley Dealer 80: ‘One of my men got washed out last night. Five slugs. He croaked, man’.

5. to fail, e.g. a course.

[US]M. Curtiss Letters Home (1944) 10 May 5: Such a great number ‘wash-out’ (fail) that I wouldn’t want anyone to know if I failed the course.
[US]L. Uris Battle Cry (1964) 49: There’s a kid [...] who wants to make Sea School but he washes out.
[US]‘Hy Lit’ Hy Lit’s Unbelievable Dict. of Hip Words 44: wash out – Fail completely.
[Aus]B. Moore Lex. of Cadet Lang. 420: usage: ‘He washed out in Chem.’.
[US]J. Ellroy ‘Stephanie’ in Destination: Morgue! (2004) 59: They checked out the Standard Club [...] The Standard Club washed out.
[US]L. Berney Whiplash River [ebook] ‘I probably should have washed out at Quantico. My first SAC actually told me that straight up’.

6. (US) vtr. to kill, to assassinate.

[US]R. Starnes Requiem in Utopia 70: There must have been a dozen opportunities to wash him out before he left London. Why wasn’t it done?