from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Formation or development of a second fetus when one is already present in the uterus, occurring normally in some animal species.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An excessive accumulation; a superfluous addition.
- n. The formation of a fetus while another fetus is already present in the uterus.
from the GNU version of the Collaborative International Dictionary of English
- 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.
from The Century Dictionary and Cyclopedia
- n. A second conception some time after a prior one, by which two fetuses of different age exist together in the same female: often used figuratively.
- n. The fetus produced by superfetation; hence, any excrescent growth.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. fertilization of a second ovum after a pregnancy has begun; results in two fetuses of different ages in the uterus at the same time
From Latin superfetare ("conceive while pregnant"), from super- + fetus. (Wiktionary)