Definition of "involution" [in•vo•lu•tion]

• The act of involving. (noun)
• The state of being involved. (noun)
• Intricacy; complexity. (noun)
• Something, such as a long grammatical construction, that is intricate or complex. (noun)
• Mathematics An operation, such as negation, which, when applied to itself, returns the original number. (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.

• "During this period the uterus undergoes what we call involution; that is, it goes back to the size and shape it had before pregnancy, and it is best not to disturb this process by sexual excitement, which causes engorgement and congestion."
• "As your uterus contracts after birth to its nonpregnant size a process called involution, you may experience periods of discomfort or pain."
• "Your uterus returns to its prepregnant size—a process called involution—about six weeks after the birth."