Col.
Colonel (abbreviated Col., Col or COL and pronounced /ˈkɜːrnəl/, similar to "kernel") is a senior military officer rank below the general officer ranks. However, in some small military forces, such as those of Iceland or the Vatican, colonel is the highest rank. It is also used in some police forces and paramilitary organizations.
Historically, in the seventeenth, eighteenth and nineteenth centuries, a colonel was typically in charge of a regiment in an army. Modern usage varies greatly.
The rank of colonel is typically above the rank of lieutenant colonel. The rank above colonel is typically called brigadier, brigade general or brigadier general.
Equivalent naval ranks may be called captain or ship-of-the-line captain. In the Commonwealth air force rank system, the equivalent rank is group captain.
The word "colonel" derives from the same root as the word "column" (Italian: colonna) and means "of a column", and, by implication, "commander of a column". The word "colonel" is therefore linked to the word "column" in a similar way that "brigadier" is linked to "brigade", although in English this relationship is not immediately obvious. By the end of the late medieval period, a group of "companies" was referred to as a "column" of an army.
Since the word is believed to derive from sixteenth-century Italian, it was presumably first used by Italian city states in that century. The first use of colonel as a rank in a national army was in the French "National Legions" (Légions nationales) created by King Francis I by his decree of 1534. Building on the military reforms of Louis XII's decree of 1509, he modernized the organization of the French royal army. Each colonel commanded a legion with a theoretical strength of six thousand men.
...
Wikipedia