[ trʌɪ'mɛstə ]
■ noun
1》 a period of three months, especially as a division of the duration of pregnancy.
2》 N. Amer. each of the three terms in an academic year.
Derivatives
trimestral adjective
trimestrial adjective
Origin
C19: from Fr. trimestre , from L. trimestris , from tri- 'three' + mensis 'month'.