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Webster 1913 Edition

Superfetation

Suˊper-fe-ta′tion

,
Noun.
[Cf. F.
superfétation
.]
(Physiol.)
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.
In then became a
superfetation
upon, and not an ingredient in, the national character.
Coleridge.

Webster 1828 Edition

Superfetation

SUPERFETA'TION

,
Noun.
A second conception after a prior one, and before the birth of the first, by which two fetuses are growing at once in the same matrix.

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