go-ahead vs red light

go-ahead

noun
  • Approval, agreement, or instruction to begin or proceed. 

adj
  • Progressive; exerting leadership. 

  • Being a score which gives the scoring team or player the lead in the game. 

  • Dashing; energetic. 

red light

noun
  • A warning light, especially as a traffic signal indicating stop. 

  • Denial to proceed; a ruling out of any possibility. 

  • A sign of a brothel. 

How often have the words go-ahead and red light occurred in a corpus of books? (source: Google Ngram Viewer )