dismiss vs sign on

dismiss

verb
  • To get a batsman out. 

  • To give someone a red card; to send off. 

  • To reject; to refuse to accept. 

  • To order to leave. 

  • To invalidate; to treat as unworthy of serious consideration. 

  • To send or put away, to discard with disregard, contempt or disdain. (sometimes followed by as). 

  • To discharge; to end the employment or service of. 

  • To dispel; to rid one’s mind of. 

sign on

verb
  • 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 join something, after signing. 

  • 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 dismiss and sign on occurred in a corpus of books? (source: Google Ngram Viewer )