hydra

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

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

Small tubular solitary freshwater hydrozoan polyp.

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”