- trimester - a period of three months; especially one of the three three-month periods into which human pregnancy is divided
--1 is a kind of time period, period of time, period
--1 is a part of gestation, gestation period
--1 has particulars: first trimester; second trimester; third trimester- trimester - one of three divisions of an academic year
--2 is a kind of school term, academic term, academic session, session
--2 is a part of school year, academic year - trimester - one of three divisions of an academic year