Bible Dictionaries
Superfetation

Webster's Dictionary

(n.) The formation of a fetus at the result of an impregnation occurring after another impregnation but before the birth of the offspring produced by it. This is possible only when there is a double uterus, or where menstruation persists up to the time of the second impregnation.

Bibliography Information
Webster, Noah. Entry for 'Superfetation'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​s/superfetation.html. 1828.