An expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements or in its grammatically atypical use of words.
Idiom:
cheat on (someone)
Meaning:
to be unfaithful to someone
Example:
The man began cheating on his wife which was the cause of their divorce.
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.