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.
spitting image of (someone)
the exact resemblance to someone
My cousin is the spitting image of his father.
List of common idioms, their meanings and examples of their usage in sentences
A group of words which have a different meaning when used together from the one they would have if you took the meaning of each word separately.