king fern king·fern uncommon noun 1. fern of rain forests of tropical Australia and New Zealand and South Africa Synonymscrepe fernking fernTodea barbara 2. large deeply rooted fern of worldwide distribution with upright bipinnate compound tufted fronds Synonymsroyal fernroyal osmundking fernditch fernFrench brackenOsmunda regalis Related words Broader terms flowering fernfern Parts Todea WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.