ENGLISH ON THE GO

An idiom is an expression,word, or phrase that has a figurative meaning that is comprehended in regard to a common use of that expression that is separate from the literal meaning or definition of the words of which it is made.

 For example: in the English expression "to kick the bucket" a listener knowing only the meanings of kick and bucket would be unable to deduce the expression's true meaning: to die.

Here we have two more useful examples.