What is a lounge suit for men, and when are they required ?

A lounge suit is a suit where the jacket and slacks/pants/trousers match each other exactly. (Source : lounge suits - definition of lounge suits by the Free Online Dictionary, Thesaurus and Encyclopedia. (http://www.thefreedictionary.com/lounge+suits) ).

Lounge suits are usually worn by businessmen when they go to work. :)