An idiom is a group of words, or in other words, a phrase that has a meaning different from the literal meaning of the words in it.
Idiom:
none the worse for wear
Meaning:
not worse because of use or effort
Example:
We were none the worse for wear after our long trip through the mountains. The bicycle was none the worse for wear after the boy used it for many months.
List of common idioms, their meanings and examples of their usage in sentences
Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.