Noun
a business suit consisting of a matching jacket and skirt or trousers
Source: WordNetIn England and Wales, black tie is seldom worn at Church weddings or civil ceremonies as morning dress or a lounge suit is normally favoured. Source: Internet
Opera Traditionally black tie should be worn to the opera although a dark lounge suit is also now acceptable. citation citation In the 21st century, many opera houses in the English-speaking world do not stipulate black tie. Source: Internet
Equivalent of the civilian lounge suit. Source: Internet