cocoon vs safeguard

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. 

safeguard

verb
  • To implement safeguarding. 

  • To escort safely. 

  • To protect, to keep safe. 

noun
  • A safe-conduct or passport, especially in time of war. 

  • Something that serves as a guard or protection; a defense. 

  • One who, or that which, defends or protects; defence; protection. 

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