Someone who spends money freely and in great amounts, especially on nonessential things or events. Can also be used sarcastically to refer to someone who is reluctant to spend money, or who offers to spend only a small amount. There are a certain few big spenders who always come through the casino, so we try to make sure they have the best experience possible. You're only willing to pay for my soda? Wow, you're a real big spender.