Green’s Dictionary of Slang

cactus adj.

[ref. to the invasive prickly pear cactus, a substantial menace in Australia until the introduction of the Catoblastus moth]

(Aus.) ruined, useless, finished, dead.

Show quotations
[Aus]J. Wynnum I’m a Jack, All Right 45: ‘Rotted right through after a while’ [...] ‘Fair go now Joe [...] It was cactus before it got anointed’.
[Aus]C. Bowles G’DAY 65: [of a car] It’s cactus. Reckon it’s been roun the clock a few times. Engine’s clapped out, an it needs a new muffler.
[Aus] (ref. to 1940s) G. Seal Lingo 66: cactus was 1940s RAAF slang for something that would not function. It experienced a revival in the 1980s, though seems to have dropped from most contemporary usage since, yet the exclamation that something is totally cactus is still met with on occasion.
[Aus]S. Maloney Sucked In 9: The paramedics got there pretty fast but he was cactus by the time we reached the hospital.
[Aus]G. Disher Peace 219: ‘The saw was cactus. They’re welcome to it’.