enter vs sign on

enter

verb
  • To become a party to an agreement, treaty, etc. 

  • To become effective; to come into effect. 

  • To go or come into (a state or profession). 

  • To cause to go (into), or to be received (into); to put in; to insert; to cause to be admitted. 

  • To place in regular form before the court, usually in writing; to put upon record in proper from and order 

  • To go into or upon, as lands, and take actual possession of them. 

  • To deposit for copyright the title or description of (a book, picture, map, etc.). 

  • To go or come into an enclosed or partially enclosed space. 

  • To type (something) into a computer; to input. 

  • To record (something) in an account, ledger, etc. 

  • To make report of (a vessel or its cargo) at the custom house; to submit a statement of (imported goods), with the original invoices, to the proper customs officer for estimating the duties. See entry. 

sign on

verb
  • To join something, after signing. 

  • To begin broadcasting a radio or television signal, usually at the beginning of a broadcasting day and after being off the air for several hours. 

  • To commit oneself, as to a project, a goal, an organization, a cause. 

  • To apply to receive unemployment benefits. 

  • To log on; to start using a computer, radio, etc., or to start talking. 

noun
  • The time of day when a radio or television station begins broadcasting, usually after being off the air for several hours. 

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