codeshare

Etymology
, because of the change in the flight's two-letter airline identity code. One aircraft will have two or more codes and flight numbers.

Noun

 * 1)  An agreement whereby an airline buys space on another airline and markets the extra space as its own. Often used to increase a route network without the costs of running a full service.

Verb

 * 1)  To buy space on (a flight) in this way.