'Sign' in the Bible

The LORD told him, "This won't happen, because whoever kills you will suffer seven times the vengeance." Then the LORD placed a sign on Cain so that no one finding him would kill him.

And God said, “This is the sign of the covenant I am making between Me and you and every living creature with you, a covenant for all future generations:

I have placed My bow in the clouds, and it will be a sign of the covenant between Me and the earth.

God said to Noah, “This is the sign of the covenant that I have confirmed between Me and every creature on earth.”

You must circumcise the flesh of your foreskin to serve as a sign of the covenant between Me and you.

They must indeed be circumcised, whether born in your house or bought with money. The sign of my covenant will be visible in your flesh as a permanent reminder.

And when God sent me wandering from my father's house, I said to her, Let this be the sign of your love for me; wherever we go, say of me, He is my brother.

And said, Praise be to the Lord, the God of my master Abraham, who has given a sign that he is good and true to my master, by guiding me straight to the house of my master's family.

And Jacob said, Not so; but if I have grace in your eyes, take them as a sign of my love, for I have seen your face as one may see the face of God, and you have been pleased with me.

And he said, I will give you a young goat from the flock. And she said, What will you give me as a sign till you send it?

Then Judah sent his friend Hirah with the young goat, to get back the things which he had given as a sign to the woman: but she was not there.

So he gave them his blessing that day, saying, You will be the sign of blessing in Israel, for they will say, May God make you like Ephraim and Manasseh; and he put Ephraim before Manasseh.