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:
make a mountain out of a molehill
Meaning:
to make a big problem out of a small problem
Example:
The man is making a mountain out of a molehill by worrying about his son`s problem.
List of common idioms, their meanings and examples of their usage in sentences
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.