A group of words which have a different meaning when used together from the one they would have if you took the meaning of each word separately.
bite the hand that feeds you
to harm or oppose someone who does good things for you
The man is biting the hand that feeds him when he criticizes and fights against his boss.
List of common idioms, their meanings and examples of their usage in sentences
The language peculiar to a people or to a district, community, or class