/ Thesaurus / S Synonyms of seed fern Find synonyms for: Noun1. seed fern, pteridosperm, gymnospermusage: an extinct seed-producing fernlike plant of the order Cycadofilicales (or group Pteridospermae)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: languid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language