A tax or fee of one cent per unit, or a charge calculated as a percentage.
Formed from 'cent' (from Latin 'centum' meaning one hundred, and also the monetary unit) plus the suffix '-age' (meaning a charge or fee). This is a specialized commercial or tax term.
This word barely survives in English because most modern taxes got more complex—but it echoes the simpler days when you just charged everyone a penny per unit.
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