Idioms
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 (something) under one's hat
Meaning:
to keep a secret, to not tell something
Example:
My coworker will not say where he is going for his holiday. He wants to keep it under his hat.
List of common idioms, their meanings and examples of their usage in sentences
The language peculiar to a people or to a district, community, or class