n.1 Med. & Zool. a second conception during pregnancy giving rise to embryos of different ages in the uterus.
2 Bot. the fertilization of the same ovule by different kinds of pollen.
3 the accretion of one thing on another.
Etymology: F superf{eacute}tation or f. mod.L superfetatio f. L superfetare (as SUPER-, fetus FOETUS)