'Adulterous' in the Bible

But He answered and said to them, “An evil and adulterous generation craves for a sign; and yet no sign will be given to it but the sign of Jonah the prophet;

An evil and adulterous generation seeks after a sign; and a sign will not be given it, except the sign of Jonah.” And He left them and went away.

For whoever is ashamed of Me and My words in this adulterous and sinful generation, the Son of Man will also be ashamed of him when He comes in the glory of His Father with the holy angels.”