Idioms
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.
Idiom:
turn one's back on (someone)
Meaning:
to refuse to help someone who is in trouble or is in need
Example:
The girl turned her back on her friend when her friend asked for help.
List of common idioms, their meanings and examples of their usage in sentences
Idioms can be a powerful linguistic tool only when they are used in the right way in the right places.