Pronunciation: (meg'u-spôr", -spōr"), [key]
1. the larger of the two kinds of spores characteristically produced by seed plants and a few fern allies, developing into a female gametophyte. Cf. microspore.
2. the embryo sac of a flowering plant. Also called macrospore.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.