(ˈ)trī|mestə(r) noun
( -s )
Etymology: French trimestre, from Latin trimestris of three months, from tri- + mensis month — more at moon
1. : a period of three or about three months
2. : one of three terms into which the academic year is divided at some educational institutions
• tri·mes·tral -strəl adjective
• tri·mes·tri·al -rēəl adjective