cocoon vs obnubilate

cocoon

verb
  • To envelop in a protective case. 

  • To withdraw into such a case. 

noun
  • The silky protective case spun by the larvae of some insects in which they metamorphose, the pupa. 

  • Any similar protective case, whether real or metaphorical. 

obnubilate

verb
  • To make cloudy. 

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