'Unchastity' in the Bible

but I say to you that everyone who divorces his wife, except for the reason of unchastity, makes her commit adultery; and whoever marries a divorced woman commits adultery.

I say to you, whoever divorces his wife, except for sexual immorality, and marries another woman commits adultery.”

Then another angel, a second one, followed, saying, “Fallen, fallen is Babylon the great, she who has made all nations drink the wine of the passion of her immorality [corrupting them with idolatry].”

For all the nations have drunk from the wine of the passion of her [sexual] immorality, and the kings and political leaders of the earth have committed immorality with her, and the merchants of the earth have become rich by the wealth and economic power of her sensuous luxury.”