admittance vs permission to enter

admittance

noun
  • Permission to enter, the power or right of entrance. 

  • The act of giving possession of a copyhold estate. 

  • The reciprocal of impedance 

  • Actual entrance, reception. 

  • The act of admitting. 

permission to enter

How often have the words admittance and permission to enter occurred in a corpus of books? (source: Google Ngram Viewer )