Reserve flightcrew member
Reserve flightcrew member means a flightcrew member who a certificate holder requires to be available to receive an assignment for duty.
14 CFR § 117.3
In addition to the definitions in 1.1 and 110.2 of this chapter, the following definitions apply to this part. In the event there is a conflict in definitions, the definitions in this part control for purposes of the flight and duty limitations and rest requirements of this part.