An idiom is defined as - a group of words whose meaning is different from the meanings of the individual words.
Idiom:
take (someone) for a fool
Meaning:
to assume that someone is stupid
Example:
The salesman tried to take me for a fool when he tried to sell me the old car.
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.