An idiom is defined as - a group of words in a fixed order that has a particular meaning that is different from the meanings of each word on its own.
Idiom:
keep the wolves at bay
Meaning:
to fight against some kind of trouble
Example:
The university students were angry and the administration had to work hard to keep the wolves at bay.
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.