A warp ship was a ship capable of warp speeds, having been equipped with a warp drive.
In his 2063 commencement address, Zefram Cochrane mentioned the first flight of his warp ship, the Phoenix which opened doors for all of Humanity. (ENT: "Regeneration")
The term was also used by several Starfleet officers in the 22nd and 24th century describing Cochrane's "experimental warp ship". (ENT: "Future Tense"; Star Trek: First Contact)
While piloting the NX-Alpha, A.G. Robinson was eager to test the warp drive and asked NX-Control for testing the warp ship. (ENT: "First Flight")
The term was also used when Captain Jonathan Archer asked Kuroda Lor-ehn if he ever piloted a warp ship and when Commander Trip Tucker asked why Enterprise NX-01 had to transport the Tellarite ambassadors, as this species had warp ships themselves. (ENT: "Canamar", "Babel One")