Other forms: regimes
A regime is a government, especially a harsh one. The former regime, regime change, under that regime.
The word is loaded: calling a government a regime signals disapproval, and no government describes itself as one. Regime change is the term for removing one, usually by outside force. The other sense is a fixed routine, especially of treatment or exercise — a training regime, a strict regime — where regimen is the more correct word and regime is what everybody says. Note regiment, which comes from the same root about ruling.
1nounregimeA government, especially a harsh one.
“The harsh military regime put thousands of its opponents in prison.”
2nounfixedA fixed routine of treatment or training.
“Her doctor put her on a strict regime of diet and exercise.”
regime is a system of rule or routine.
Latin regimen means direction or government, from regere, to rule — the same verb as regent, regular and rule. A regime and a regimen are the same word, and English split them by spelling rather than by sense.
Proto-Indo-European
*h₃reǵ-
Latin
regimen — direction, government
Middle French
regime
Middle English
regime
English, today
regime
From Middle English regime, regyme, from Middle French regime, from Latin regimen (“direction, government”). a doublet of regimen.
Etymology from Wiktionary, CC BY-SA