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:
not by a long shot
Meaning:
not at all
Example:
Not by a long shot was I able to find enough time to finish reading the book.
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.