adj.
Function: adjective
Date: circa 1541
1 : engaged in an activity or function (as a dramatic role)
2 a (1) : being in operation <the radio is on > (2) : placed so as to permit operation <the switch is on > b : taking place or being broadcast <the game is on >
3 : aware of something ― usually used with to <my boss was on to me>
4 : INTENDED , PLANNED <has nothing on for tonight>
5 British : talking or harping incessantly ― used with about
6 chiefly British : regarded as possible or feasible ― usually used in negative constructions
7 a : engaged in or as if in a performance <the comedian was always on > b : being at a high level of performance