The USS Excelsior (NX-2000, later NCC-2000) was a Federation Excelsior-class starship that was in service with Starfleet from the late 23rd century. Excelsior was the prototype for her class of starship.
Dubbed "The Great Experiment," the Excelsior was conceived during the early 2280s as the first Starfleet vessel equipped with transwarp drive. An awe-inspiring concept to some, traditional engineers were more skeptical, as in the case of Montgomery Scott, who expressed his doubt in transwarp technology with the analogy, "and if my grandmother had wheels, she'd be a wagon."
Designed under radically new principles of propulsion, the Excelsior had the potential for becoming the fastest starship in the entire Federation, as at that time, the Starfleet record for faster-than-light travel was warp factor 14.1, set by the USS Enterprise in 2269.