HYDRA
WordNet
noun
(1) Small tubular solitary freshwater hydrozoan polyp
(2) Trouble that cannot be overcome by a single effort because of its many aspects or its persistent and pervasive quality
"We may be facing a hydra that defies any easy solution"
(3) A long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer
(4) (Greek mythology) monster with nine heads; when struck off each head was replaced by two new ones
"Hydra was slain by Hercules"
WiktionaryText
Noun
- Any of several small freshwater polyps of the genus Hydra and related genera, having a naked cylindrical body and an oral opening surrounded by tentacles.