An idiom is a group of words, or in other words, a phrase that has a meaning other than its literal meaning of the words in it.
top (someone or something)
to do or be better than someone or something
The young woman topped everyone in her class with her excellent science project.
List of common idioms, their meanings and examples of their usage in sentences
Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.