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.
smack into (someone or something)
to collide or hit someone or something
The car smacked into the car in front of it.
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.