"hydras" in the noun sense

1. Hydra

Greek mythology) monster with nine heads when struck off each head was replaced by two new ones

"Hydra was slain by Hercules"

2. Hydra, Snake

a long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer

3. hydra

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"

4. hydra

small tubular solitary freshwater hydrozoan polyp

Source: WordNet® (An amazing lexical database of English)

Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.

View WordNet® License