A dial is the part of a machine or instrument such as a clock or watch which shows you the time or a measurement that has been recorded.

A dial is a control on a device or piece of equipment which you can move in order to adjust the setting, for example to select or change the frequency on a radio or the temperature of a heater.

On some telephones, especially older ones, the dial is the disc on the front that you turn with your finger to choose the number that you want to call. The disc has holes in it, and numbers or letters behind the holes.

If you dial or if you dial a number, you turn the dial or press the buttons on a telephone in order to phone someone.