Pronunciation: (prē"fôr-mā'shun), [key]
1. previous formation.
2. Biol.(formerly) the theory that the individual, with all its parts, preexists in the germ cell and grows from microscopic to normal proportions during embryogenesis (opposed to epigenesis).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.