a suit, especially one of conservative cut and color.Compare suit(defs 2, 3).
Origin of business suit
An Americanism dating back to 1865–70
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for business suit
To this officer a sack-suit or business-suit is a lounge-suit.The American Language|Henry L. Mencken