from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The concave underside of the body of a jellyfish.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The integument of the undersurface of the bell, or disk-shaped body, of a jellyfish.
from the GNU version of the Collaborative International Dictionary of English
- n. The integument of the under surface of the bell, or disk-shaped body, of a jellyfish.
from The Century Dictionary and Cyclopedia
- n. The internal ventral or oral disk of a hydrozoan, as a jellyfish; the muscular layer beneath the umbrella or swimming-bell of a hydromedusan, continuous with the velum.
sub- + umbrella (Wiktionary)