Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.
reputed to be/do something
to be thought to do or be or have something
The new police chief is reputed to be the best police chief in the country.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is a type of phrase or expression that has a meaning that can't be deciphered by defining the individual words.