trimester

Từ điển Oxford Advanced Learner 8th

tri·mes·ter [trimester trimesters] BrE [traɪˈmestə(r)] NAmE [traɪˈmestər] noun
1. (medical)a period of three months during the time when a woman is pregnant
•the first trimester of pregnancy
2. (NAmE) = ↑term
•The school year is divided into three trimesters.
compare ↑semester

Word Origin:
early 19th cent.: from French trimestre, from Latin trimestris, from tri- ‘three’ + mensis ‘month’.