To pay a sum of money, especially one that seems exorbitant or unfair. A noun or pronoun can be used between "shell" and "out" to specify the amount being paid. They said I had to shell out $200 to cancel my contract early! I know it's a lot of money, but you'll have to shell out if you want to join in. I'm going to have to shell nearly $3,000 out for a new water heater!