- a man's suit that has a loose-fitting jacket.
Origin of sack suit
An Americanism dating back to 1890–95
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for sack suit
To this officer a sack-suit or business-suit is a lounge-suit.
Pratt came in quite briskly, a heavy-faced, white-bearded man, wearing a sack-suit and an old-fashioned turn-down collar.