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.
Idiom:
pound out (something) or pound (something) out
Meaning:
to type something on a typewriter, to play a song on a piano
Example:
I spent several hours trying to pound out an essay on my computer.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is a widely used saying or expression containing a figurative meaning that differs from the phrase's literal meaning.