Refers to moving the camera horizontally without changing the direction in which it points (that would be a Pan). Usage: "truck left," "truck right." Moving closer to or away from the subject is referred to as a dolly.
Sometimes referred to as "Track" or "Tracking Shot", although "truck" is the correct term.
Contrast Pan, horizontally rotating the camera to get a grasp of the panorama. Super-Trope of Conveyor Belt Video (the camera continuously tracks to one side, creating the illusion of filming on a conveyor belt).
Don't confuse with Loudspeaker Truck, when a passing vehicle makes a very loud noise to indicate awkwardness.