in park
Of a vehicle, having the gear stick set to "park," which keeps the vehicle in place in a manner similar to a parking brake. A: "How did the car roll forward like that?" B: "Are you sure you had it in park?" Oh yeah, you're close enough to the curb. Go ahead, put the car in park.
in park
[of an automobile transmission] having the gears locked so the automobile cannot move. The driver stopped the car and placed it in park. You have to be in park in order to start this car.