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:
look in on (someone)
Meaning:
to go to see someone, to make a short visit to someone, to make a call on someone to see if he or she is doing well
Example:
"Could you please look in on the baby and see if she is sleeping."
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.