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medical 医学 a period of three months during the time when a woman is pregnant 妊娠期（以三个月为单位） the first trimester of pregnancy 妊娠的头三个月
- (North American English) (also term especially in British English)
one of the three periods in the year during which classes are held in schools, universities, etc. 学期（学校一年分三个学期）
Word Originearly 19th cent.: from French trimestre, from Latin trimestris, from tri- ‘three’ + mensis ‘month’.