An idiom is defined as - a group of words whose meaning is different from the meanings of the individual words.
Idiom:
turn over (an engine)
Meaning:
to start an engine or motor
Example:
It was very cold in the morning so the car engine would not turn over easily.
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.