hydra vs torment

hydra

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. 

  • A dragon-like creature with many heads and the ability to regrow them when maimed. 

  • A complex, multifarious problem or situation that cannot be solved easily and rapidly. 

torment

verb
  • To cause severe suffering to (stronger than to vex but weaker than to torture.) 

noun
  • Any extreme pain, anguish or misery, either physical or mental. 

  • Torture, originally as inflicted by an instrument of torture. 

How often have the words hydra and torment occurred in a corpus of books? (source: Google Ngram Viewer )