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:
too many irons in the fire
Meaning:
to have too many things that you are trying to do
Example:
My friend has too many irons in the fire at the moment and has no time for other things.
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.