From Medieval Latin *denarius*, the name of a Roman silver coin. The *denarius* was so ubiquitous in trade that it became the generic word for money across the Iberian Peninsula, giving Spanish *dinero* and Portuguese *dinheiro*.

Brazilians commonly use *dinheiro* to mean physical cash specifically, as opposed to *cartão* (card) — so "você paga em dinheiro ou cartão?" ("cash or card?") is a standard question at checkouts. The slang *grana* and *bufunfa* are informal alternatives you'll hear in everyday speech.