to use money to buy something, or to pass time doing something.
From Old French 'despendre' and Latin 'dispendere' (dis- + pendere 'to weigh/pay'). Originally meant 'to weigh out' payment, later generalized to any use of resources.
The root 'pendere' means 'to weigh'—think of a scale! Ancient commerce literally involved weighing out valuable materials, so 'spend' originally meant weighing out your payment for something.
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