impress vs sign on

impress

verb
  • To compel (someone) to serve in a military force. 

  • To mark or stamp (something) using pressure. 

  • To fix deeply in the mind; to present forcibly to the attention, etc.; to imprint; to inculcate. 

  • To seize or confiscate (property) by force. 

  • To make an impression, to be impressive. 

  • To produce a vivid impression of (something). 

  • To affect (someone) strongly and often favourably. 

  • To produce (a mark, stamp, image, etc.); to imprint (a mark or figure upon something). 

noun
  • An impression; an impressed image or copy of something. 

  • The act of impressing. 

  • Characteristic; mark of distinction; stamp. 

  • The act of impressing, or taking by force for the public service; compulsion to serve; also, that which is impressed. 

  • An impression on the mind, imagination etc. 

  • A heraldic device; an impresa. 

  • A stamp or seal used to make an impression. 

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