[meg-uh-spawr, -spohr]
noun Botany.
  1. the larger of the two kinds of spores characteristically produced by seed plants and a few fern allies, developing into a female gametophyte.Compare microspore.
  2. the embryo sac of a flowering plant.

Origin of megaspore

First recorded in 1885–90; mega- + spore
Also called macrospore.
Related formsmeg·a·spor·ic [meg-uh-spawr-ik, -spor-] /ˌmɛg əˈspɔr ɪk, -ˈspɒr-/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for megaspore

Historical Examples of megaspore

British Dictionary definitions for megaspore


  1. Also called: macrospore the larger of the two types of spore produced by some spore-bearing plants, which develops into the female gametophyteCompare microspore (def. 1)
  2. the cell in flowering plants that gives rise to the embryo sac
Derived Formsmegasporic, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for megaspore

1857, from mega- + spore.

Online Etymology Dictionary, © 2010 Douglas Harper

megaspore in Science


  1. One of the two types of haploid spores produced by a heterosporous plant. Megaspores develop into female gametophytes and are usually larger than microspores.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.