Rhizostomata
Rhi`zo`stom´a`ta
| n. pl. | 1. | (Zool.) A suborder of Medusæ which includes very large species without marginal tentacles, but having large mouth lobes closely united at the edges. See Illust. in Appendix. |
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.