Where "Crook" Comes From
"Crook" in Australian English means ill or unwell — "feeling crook" — or more broadly, bad, unfair, or wrong — "that's a bit crook." The word derives from Middle English "croke/crok" (a hook or bend), whose figurative extension to "dishonest" or "criminal" is recorded from the 17th century. In Australian slang, the additional sense of "sick" or "in poor condition" emerged in the late 19th century, building on the existing sense of "bad" or "defective."
In practice, "crook" does a lot of work in Australian English. It can describe a physical state ("I've been crook all week"), a moral judgment ("that's a crook thing to do"), or a piece of equipment ("the engine's gone crook"). "Go crook at" means to get angry with and tell off — as in "she went crook at him for being late." The Macquarie Dictionary has documented the word's semantic spread across these registers, noting that its range exceeds what any single English equivalent can cover.
"I'm feeling crook, might chuck a sickie."
How Aussies Actually Use It
"Feeling crook" is the go-to phrase for being unwell, used for humans and pets alike, and stretching to describe an injured or aching body part, like a "crook back."
It also covers anything unsatisfactory or in poor shape more generally — a crook attitude, a crook deal — and, in older or rural use, describes someone genuinely angry, as in "she went crook at me."
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