flower-of-an-hour flo·we·ro·fanhour uncommon noun 1. annual weedy herb with ephemeral yellow purple-eyed flowers; Old World tropics; naturalized as a weed in North America Synonymsflowers-of-an-hourbladder ketmiablack-eyed SusanHibiscus trionum Related words Broader terms hibiscus WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
