trimester
Word family nountrimesteradjectivetrimestrial
tri·mes·ter /trɪˈmestə $ traɪˈmestər/ noun [countableC] 1. American EnglishAmESE one of three periods of equal length that the school year is divided into 〔一学年三学期中的〕一学期 SYN British English term 2. MBone of the three-month periods of pregnancy 〔妊娠三期中的〕一期 Origin trimester (1800-1900) French trimestre, from Latin trimestris, from tri- “three” + mensis “month”