adjective: (telecommunications) Relating to activity outside of a defined telecommunications frequency band.
adjective: (telecommunications, by extension) Relating to communication on a different channel, or by a different method, from that of the primary communication channel.
adjective: (computer security) Relating to communication, such as identity verification, via a method other than the primary means of accessing the software.
adjective: (programming) Referring to a value returned by a function that is not in its natural range of return values, but rather signals an exception.
