What does the word signal mean?

Usage examples for signal

  1. We landed, however, whenever we saw a spot where we thought it possible our friends might have touched on their voyage, in the hope that they might there have left some signal or note for us. – On the Banks of the Amazon by W.H.G. Kingston
  2. That would be the signal for them all to turn and go home, Ken thought. – The Year When Stardust Fell by Raymond F. Jones
  3. And even on this day it had not occurred to her that the Signal might be worth opening. – The Old Wives' Tale by Arnold Bennett