Question

What is an idiom?

an intentional exaggeration used to create an effect
a human trait or feeling given to a nonhuman thing
a word or phrase that sounds like the sound it describes when spoken
an expression with a meaning other than that of the words that make it up

Answer 1

An idiom is "an expression with a meaning other than that of the words that make it up."
Example: "It's raining cats and dogs" means it's raining heavily, not literally animals falling from the sky.