Definition of "trimester" []

• A period or term of three months. (noun)
• One of three terms into which an academic year is divided in some universities and colleges. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "You may hear the word trimester period of three months a lot while you’re pregnant."
• "Exposure in the first trimester is particularly toxic, and unfortunately this is often before many women realize they are pregnant."
• "Pregnant couples are “supposed to” hang on to their secret until the first trimester is over."