The phrase "flannel suit" refers to a type of formal clothing made of flannel fabric. It typically describes a suit, consisting of matching pants and jacket, that is made from soft and warm material. Full definition
The gray flannel suit, they point out, was a phenomenon in only a few urban areas and in only a few occupations. (religion-online.org)
Perfect for teaming with a pair of casual jeans and a simple tee for a day out or you can dress them up for he office with a dark grey flannel suit. (theidleman.com)
• The Horse in the Gray Flannel Suit Tim Conway: The World's Greatest Athlete • The Apple Dumpling Gang • The Apple Dumpling Gang Rides Again Suzanne Pleshette: The Adventures of Bullwhip Griffin • The Lion King II: Simba's Pride • Spirited Away Dick Van Patten: The Strongest Man in the World • Freaky Friday Richard Bakalyan: Follow Me, Boys! (dvdizzy.com)