In very technical language: The frequency of the unmodulated electromagnetic wave at the output of a conventional amplitude-modulated (AM-unsupressed carrier), or frequency-modulated (FM), or phase-modulated (PM) radio transmitter
In very technical language: The nominal frequency or center frequency of various kinds of radio signals with digital modulation -- provided that the message bit stream is a random uncorrelated sequence of equally probable ones and zeroes ("marks" and "spaces")