decidua

noun

1
: the part of the endometrium that in higher placental mammals undergoes special modifications in preparation for and during pregnancy and is cast off at parturition
2
: the part of the endometrium cast off in the process of menstruation

Word History

Etymology

New Latin, from Latin, feminine of deciduus

First Known Use

1785, in the meaning defined at sense 1

Time Traveler
The first known use of decidua was in 1785

Browse Nearby Words

Cite this Entry

“Decidua.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/decidua. Accessed 11 Mar. 2025.

Medical Definition

1
: the part of the mucous membrane lining the uterus that in higher placental mammals undergoes special modifications in preparation for and during pregnancy and is cast off at parturition, being made up in the human of a part lining the uterus (see decidua parietalis), a part enveloping the embryo (see decidua capsularis), and a part participating with the chorion in the formation of the placenta (see decidua basalis)
2
: the part of the mucous membrane of the uterus cast off in the ordinary process of menstruation
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