'Sign' in the Bible

Then certain of the scribes and Pharisees answered him, saying, Teacher, we would see a sign from thee.

But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given it but the sign of Jonah the prophet:

And the Pharisees and Sadducees came, and trying him asked him to show them a sign from heaven.

An evil and adulterous generation seeketh after a sign; and there shall no sign be given unto it, but the sign of Jonah. And he left them, and departed.

And as he sat on the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what'shall be the sign of thy coming, and of the end of the world?

and then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming on the clouds of heaven with power and great glory.

Now he that betrayed him gave them a sign, saying, Whomsoever I shall kiss, that is he: take him.