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:
put the cart before the horse
Meaning:
to do things in the wrong or usual order
Example:
I think that my friend is putting the cart before the horse to talk about remodeling the house before he buys it.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is a type of phrase or expression that has a meaning that can't be deciphered by defining the individual words.