Meaning

noun the face of a timepiece; graduated to show the hours

noun the control on a radio or television set that is used for tuning

noun the circular graduated indicator on various measuring instruments

originThe original meaning was 'sundial' and/or 'clock dial'; from Middle English diall, from Middle French dyal, from Latin diālis (“daily, concerning the day”), because of its use in telling the time of day, from Latin diēs (“day”). Compare Spanish dial and día (“day”).

Etymology from Wiktionary, CC BY-SA 3.0