Where "Zac" Comes From
"Zac" (sometimes spelled "zack") entered Australian slang in the 1890s as a nickname for the sixpence coin, back when Australia used pounds, shillings, and pence. It was small change even then — enough for a newspaper or a lolly, not much more.
When Australia switched to decimal currency in 1966, the sixpence disappeared, but "zac" lived on in the language, mostly through the phrase "not worth a zac" — meaning something is worthless or barely worth anything at all.
"That old car isn't worth a zac these days."
How Aussies Actually Use It
These days almost nobody uses "zac" to mean an actual amount of money — it survives almost entirely in the fixed phrase "not worth a zac," describing something of little or no value.
It's a nostalgic bit of slang, most often used by older Australians, though the phrase itself is still widely understood across generations.
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