Read the dictionary definition of hydra. All definitions for this word.
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
1. 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
1. Hydra was slain by Hercules