levy vs sign on

levy

verb
  • To raise; to collect; said of troops, to form into an army by enrollment, conscription. etc. 

  • To raise, as a siege. 

  • To raise or collect by assessment; to exact by authority. 

  • To erect, build, or set up; to make or construct; to raise or cast up. 

  • To draft someone into military service. 

  • To wage war. 

  • To impose (a tax or fine) to collect monies due, or to confiscate property. 

noun
  • The tax, property or people so levied. 

  • The act of levying. 

sign on

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

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