trimester

Meanings

1. 1nouncountablemedical

   One of the three roughly three-month periods into which a pregnancy is divided.

   Grammar: Countable; usually used with an ordinal number: the first trimester, the second trimester.

   Patterns

   • the first/second/third trimester
   • in the first trimester
   • during the second trimester

   She had severe morning sickness during her first trimester.

   Most women feel more energetic in the second trimester.

   The baby's major organs form in the first trimester.

2. 2nouncountable

   One of three main periods that make up a school or university year.

   Grammar: Countable; often used with at or in: at the start of the trimester.

   Patterns

   • the fall/spring trimester
   • in the first trimester
   • a trimester system

   The university divides its year into three trimesters.

   He took a heavy course load in the fall trimester.

   Students on the trimester system finish their exams in early December.

3. 3nouncountableformal

   A period of about three months, used as a unit of time.

   Grammar: Countable; often followed by of: a trimester of treatment.

   Patterns

   • a trimester of something
   • every trimester
   • for a trimester

   The project was reviewed every trimester.

   She spent a trimester working abroad.

   The committee meets once a trimester.

Word forms

Common combinations

first trimester

The first trimester is often the most tiring.

second trimester

She started feeling better in the second trimester.

third trimester

Back pain is common in the third trimester.

trimester system

The school switched to a trimester system last year.

fall trimester

Registration for the fall trimester opens in August.

Synonyms and how they differ

term

A more general word for any fixed period of study; it does not necessarily mean one of three.

semester

One of two main periods in a school year, rather than one of three.

quarter

A similar academic period, but usually lasting about ten to twelve weeks.

Word family

trimestral adjective

Happening every three months or relating to a trimester.

Commonly confused: trimester or semester? trimester or quarter?

Practice

Make it your own

Write a sentence using “trimester”, then check it and compare it with the examples above.

Explore more words