Plural of dacker; multiple people who dack, or Australian slang for trousers/pants (from 'Dacca' cotton).
From 'dacker' plus the plural suffix '-s.' The clothing meaning may derive from 'Dacca' (a type of fine cotton), which is where durable trousers were historically made.
The Australian slang 'dackers' for trousers shows how fabric names can become clothing names—just as 'denim' comes from the city of Nîmes, 'dackers' comes from Dacca cotton, and both reveal how trade and manufacturing influenced what we call things.
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