cocoon vs engulf

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. 

engulf

verb
  • To surround; to cover; to submerge. 

  • To overwhelm. 

  • To cast into a gulf. 

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