noun. a narrow, elongated depression, groove, notch, slit, or aperture, especially a narrow opening for receiving or admitting something, as a coin or a letter. a place or position, as in a sequence or series: The program received a new time slot on the broadcasting schedule.

As their name suggests, penny slots are slot machines that can be played for as little as one cent per spin. They're a pretty old model, and, even though lots of modern casinos have kept them, most slots nowadays have more than one payline, sometimes over 50.