Colonel Definition

kûrnəl

noun

A military officer ranking above a lieutenant colonel and below a brigadier general, and corresponding to a captain in the navy.

Webster's New World

One who holds this rank or a similar rank in another military organization.

American Heritage

An honorary, nonmilitary title in some Southern or Western U.S. states.

Webster's New World

Other Word Forms of Colonel

Singular:

colonel

Plural:

colonels

First attested 1548, from Middle French coronel, from Old Italian colonnello (“the officer of a small company of soldiers (column) that marched at the head of a regiment”), from compagna colonnella (“little column company”), from Latin columna (“pillar”), originally a collateral form of columen, contraction culmen (“a pillar, top, crown, summit”), o-grade form from a Proto-Indo-European *kʷel- (“going around”).

From Wiktionary
Alteration of obsolete coronel from French from Old Italian colonello from diminutive of colonna column of soldiers from Latin columna column kel-² in Indo-European roots

From American Heritage Dictionary of the English Language, 5th Edition