noun.
The diploid spore-producing phase in the life cycle of a plant that exhibits alternation of generations. It is the dominant stage in vascular plants.
The Century Dictionary and Cyclopedia
noun.
In botany, the segment or stage of the life-cycle of the higher cryptogams (Pteridophyta, Bryophyta) in which the non-sexual organs of reproduction are borne
the GNU version of the Collaborative International Dictionary of English
noun.
In plants exhibiting alternation of generations, the generation which bears asexual spores; -- opposed to gametophyte. It is not clearly differentiated in the life cycle of the lower plants.