trimester

1. N-COUNT The first trimester of a pregnancy is the first three months of the pregnancy. The second trimester is the period from three months to six months, and the third trimester is the period from six months to nine months. (怀孕期的)三个月

At the end of the first trimester, the fetus is about three inches long. 在怀孕的第三个月末，胎儿差不多有三英寸长了。

2. N-COUNT In colleges and universities in some countries, a trimester is one of the three main periods into which the year is divided. (一些国家的学院及大学中一学年的三分之一)学期

...the proposed school's trimester calendar. ...这份拟定的学校学期日历。