Colonel

Colonel (pronounced KUR-nal) is a military rank, the equivalent of which is used by the service organizations of many civilizations. As a traditional grade, Colonel is the most senior line officer rank of a fighting organization, below the flag rank of General and senior to the rank of Major. In comparison to naval ranking systems, this rank is equivalent to the naval Captain rank, the Romulan Star Empire's Commander grade, the Ferengi Alliance's Daimon, or the Cardassian Union's title of Gul. A Colonel commands a brigade, an army unit consisting of a variable number (but not less than two) regiments.

Some rank systems have an additional grade, lieutenant Colonel, which falls between Colonel and Major.

From Memory Alpha -- the free Star Trek reference