Green’s Dictionary of Slang

(Aus./N.Z.) a wound sufficiently severe to ensure that the recipient is invalided off the battlefield and back home; thus the individual who suffers such a wound.

1943		Sydney Morn. Herald 11 Dec. 7/3: If a man is wounded he gets a ‘Blighty’ [...] or a ‘homer’.
1944		Ellesmere Guardian (Canterbury) 8 Feb. 2/2: A cobber [...] who went back to New Zealand perhaps, as a ‘homer’.
1952		T.A.G. Hungerford Ridge and River (1966) 173: He’ll get a homer out of it — perhaps Australia.
1970		(con. 1941) R. Beilby No Medals for Aphrodite 164: ‘Bad?’ The lieutenant’s voice was troubled. ‘Yeah. Looks like a homer. He’s all bust up in the crutch.’.
2005		(con. 1940–43) M. Thompson Our War 255: For the wounded soldier the ‘ideal’ wound was a ‘homer’ – not too damaging or disfiguring.
2007		(con. c.1970) G. Lockhart Minefield 155: Lees was blown sky-high [...] Heron, covered in blood from stomach wounds, stood looking at Lees and said: ‘You’ve got a homer there, Sarge.’.