The definition of on-air is something that is broadcast over the radio or on TV.
A comment that a TV host makes on a live TV show is an example of an on-air comment.
(while) broadcasting or being broadcast
Spoken, occurring, or used during broadcasting: an on-air gaffe; changed his on-air name.
- Broadcast (as opposed to recorded).
- Actually broadcasting on a radio or television station (as opposed to just recording for later transmission).
- He didn't realise he had made his remarks on-air.
Derived from early use of radio, literally sending the transmission on the air waves
- on the air