A Federation starship of the 2370s whose chief medical officer was Elizabeth Lense, the classmate who beat Julian Bashir to first place at Starfleet Medical.
This USS Lexington is a 24th-century Federation starship, a later ship of the name carried by Commodore Wesley's vessel in the original series. It visits Deep Space 9 in the episode Explorers, set in 2371.
Julian Bashir is anxious about the visit because the ship's doctor, Elizabeth Lense, graduated first in their class while he came second. When she walks past him in Quark's without a glance he assumes she is snubbing him. In fact she had always believed that Bashir was an Andorian, having had the wrong man pointed out to her at a party.
The two end up talking through the night. Lense admits that she envies him his post, since the Lexington's long charting missions give her little chance for sustained research.