Is it ensure, insure, or assure?
"system of government or rule," 1792, from French régime, from Old French regimen (14c.), from Latin regimen "rule, guidance, government, means of guidance, rudder," from regere (see regal). Earlier "course of diet, exercise," late 15c. In French, l'ancien régime refers to the system of government before the revolution of 1789.
regime re·gime (rā-zhēm', rĭ-)
A regulated system, as of diet and exercise; a regimen.
An administration, or a system of managing government.