noun

• (military) A unit of armed troops under the command of an officer, and consisting of several smaller units.
  "It was an old, withered man, who had served the Government in the days of the Mutiny as a native officer in a newly raised cavalry regiment."
• (now rare, archaic) Rule or governance over a person, place etc.; government, authority.
  "What place is there in all the world, not ſubiect to the regiment and power of this citie?"
• (obsolete) The state or office of a ruler; rulership.
  "But this it is that doth excruciate The verie ſubſtance of my vexed ſoule: To ſee our neighbours that were wont to quake And tremble at the Perſean Monarkes name, Now ſits and laughs our regiment to ſcorne, […]"
• (obsolete) Influence or control exercised by someone or something (especially a planet).
  "Nature that fram’d vs of foure Elements, Warring within our breaſts for regiment, Doth teach vs all to haue aſpyring minds:"

verb

• (transitive) To form soldiers into a regiment.
  "J. W. Powell The people are organized or regimented into bodies, and special functions are relegated to the several units."
• (transitive) To systematize, or put in rigid order.
  "The result was a tidy, law-abiding country, but one that visitors often described as regimented, sterile and dull."