Warp core is the common term used to describe the for the main reactor of starship warp engines. Federation designed warp cores usually consists of a matter/antimatter reaction assembly (M/ARA), powered by dilithium crystals and/or deuterium and anti-deuterium. Warp cores aboard some Romulan starships were powered by an artificial quantum singularity. The term was not used until Star Trek: The Motion Picture, but was nonetheless heard in the Star Trek: Enterprise. In the event of an imminent warp core breach or other emergency, the core can be ejected into space.