Definition of: archegonium

(är′kə·gō′nē·əm) noun plural ·ni·a (-ne·ə) Bot.
The female sexual organ of the higher cryptogams, the analog of the pistil of flowering plants, which has, when ready for fertilization, the form of a cellular sac or flask containing an egg-cell. Also ar·che·gone (är′kə·gōn). [<NL <Gk. archegonos primitive parent <archos chief, first + gonos offspring]
—ar′che·go′ni·al adjective
—ar′che·go′ni·ate (-it, -āt) adjective