REGIMENT (from Late Latin regimentum, rule, regere, to rule, govern, direct), originally government, command or authority exercised over others, or the office of a ruler or sovereign; in this sense the word was common in the 16th century. The most familiar instance is the title of the tract of John Knox, the First Blast of the Trumpet against the Monstrous Regiment of Women. The term as applied to a large body of troops dates from the French army of the 16th century. In the first instance it implied " command," as nowadays we speak of " General A's command," meaning the whole number of troops under his command. The early regiments had no similarity in strength or organization, except that each was under one commander. With the regularization of armies the commands of all such superior officers were gradually reduced to uniformity, and a regiment came to be definitely a colonel's command. In the British infantry the term has no tactical significance, as the number of battalions in a regiment is variable, and one at least is theoretically abroad at all times, while the reserve or territorial battalions serve under a different code to that governing the regular battalions. The whole corps of Royal Artillery is called " the Royal Regiment of Artillery." In the cavalry a regiment is tactically as well as administratively a unit of four squadrons. On the continent of Europe the regiment of infantry is always together under the command of its colonel, and consists of three or four battalions under majors or lieutenant-colonels.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)