'Sign' in the Bible

And a great sign was seen in heaven: a woman arrayed with the sun, and the moon under her feet, and upon her head a crown of twelve stars;

And there was seen another sign in heaven: and behold, a great red dragon, having seven heads and ten horns, and upon his heads seven diadems.

And I saw another sign in heaven, great and marvellous, seven angels having seven plagues, which are the last, for in them is finished the wrath of God.