Green’s Dictionary of Slang

bosh v.

1. to spoil, to render useless.

1710		R. Steele Tatler No. 71 n.p.: When to the plain Garb of Gown and Band a Spark adds an inconsistent long Wig, we do not say now he Boshes, but there goes a Smart Fellow.
1869		Macmillan’s Mag. (London) XXI 71: You ‘bosh’ his joke [a man’s] by refusing to laugh at it; you ‘bosh’ his chance of sleep by playing upon the cornet all night in the room next to him.
1870		see sense 2 .
1883		M.E. Braddon Golden Calf xiv: ‘And wouldn’t he make a jolly schoolmaster?’ exclaimed Reginald. ‘Boys would get on capitally with Jardine. They’d never try to bosh him.’ [F&H].
1887		‘’Arry in the Witness-Box’ in Punch 5 Feb. 61/2: That bloomin’ old Beak! / He boshed all my patter to putty, and snubbed all my snideness as cheek.
1888		‘’Arry on Competitive Examination’ in Punch 1 Dec. 253/2: Exams are all evil, / And if we don’t bosh up that bizness Old England will go to the devil.

2. to cause trouble for; to irritate.

1870		Argus (Melbourne) 15 Jan. 1/6: Oxford claims the credit of having invented tho verb ‘to bosh.’ Its meaning is much the same as that of the kindred verb, ‘to hustle.’ [...] Both [...] mean something like ‘to balk,’ ‘to annoy,’ or (when applied to things) ‘to spoil’ .
1891		‘’Arry on Wheels’ in Punch 7 May 217/2: Don’t I jest discumfuddle the donas, and bosh the old buffers as prowl/ Along green country roads.

In compounds

bosh-shot (n.) [SE shot]

a bad shot, an unsuccessful attempt.

1939

‘George Orwell’ Coming Up For Air in Complete Works (1986) 155: The lecturer was describing how the Nazis chop people’s heads off for treason and sometimes the executioner makes a bosh shot.

In phrases

bosh up (v.)

to go bankrupt.

1885		Bulletin (Sydney) 24 Jan. 12/1: Christmas nearly ‘boshed up’ the Harmy. Half the soldiers went on the bust – 250 pawned their uniforms; bassoons and trombones were also freely offered to ‘Moshish.’.
1923		J. Manchon Le Slang.