Admiral

Admiral is a military rank, the equivalent of which is used by the service organizations of many civilizations. As a traditional grade, admiral is the most senior flag officer rank of a naval organization, senior to a captain. Admirals command fleets of ships, as opposed to captains commanding single ships or units. In comparison to other ranking systems, this rank is equivalent to the infantry/fighting general rank or the Cardassian Union's quasi-military rank of legate.

From Memory Alpha -- the free Star Trek reference