slang A physician or medical clinic that one is able to access on a walk-in basis or at any time of day. A play on "McDonald's," the fast food chain, and "doc," short for "doctor." She decided to join a growing number of McDocs who work in urgent care clinics. There's a McDoc on Main Street if you want to go in for a checkup. You might be stuck in the waiting room for a while, but it's free.