trimestrer

Trimestrer is a term used to denote a period of three months, typically divided into three equal parts. The standard English form is trimester; trimestrer appears as an alternate spelling in some languages or as a nonstandard variant. The concept applies in pregnancy, education, and other contexts requiring three-month segments.

In obstetrics, pregnancy is commonly divided into three trimesters. The first trimester covers roughly weeks 1–12, the second weeks 13–26, and the third weeks 27–40, though exact cutoffs vary by guideline. Trimesters are used for planning prenatal care, screening, and risk assessment, and health information often references milestones by trimester.

In education, a trimester system divides the academic year into three terms, each typically spanning about 12–14 weeks. Courses may run within a single term or extend across multiple terms. A trimester calendar affects scheduling, credit accrual, and assessment timing; many systems use semesters or quarters instead, depending on country and institution.

Outside medicine and schooling, the term can denote any three-month segment within a calendar or fiscal year, used for reporting or budgeting. The exact dates of a trimester are defined by the governing calendar in use.

Derived from Latin tri- 'three' and mensis 'month,' the common English spelling is trimester; trimestrer is rare and typically a misspelling or dialectal variant. The meaning and boundaries of a trimester depend on domain and regional convention.