disapproval If you call someone a spendthrift, you mean that they spend too much money. Spendthrift is also an adjective. his father's spendthrift ways. someone who spends money carelessly, even when they do not have a lot of it (spend + thrift (14-19 centuries))
One who spends money profusely or improvidently; a prodigal; one who lavishes or wastes his estate