This is the least-understood term of dress. "Informal" really describes a dressy occasion, but the term is often confused with "casual." Think of “informal” as having the same root word as “formal”; it’s just one step removed from that. Sometimes, an invitation will state, “Civilian Informal,” meaning civilian-style informal clothes for the military, not uniforms. Other more descriptive terms often used for informal functions are, "Business Suit" and "Coat and Tie."
Military informal function — The invitation will state the uniform, usually Army Blues with four-in-hand tie (long tie). The four-in-hand tie is always worn with Army Blues and Army Whites at functions held in the afternoon and those that begin before Retreat.
Civilian informal function — When the invitation says "Informal," men are expected to wear a suit — a dark (subdued) business suit with tie. The phrase “Coat and Ties” is a shade less demanding because this implies that men may wear a suit or sports jacket — but always with a tie for informal functions.
An informal function requires a dressy dress; just how dressy depends on: the type of function, time of day, hostess' preference, and local customs. An informal dinner-party invitation usually means that the ladies will wear dressy clothes, jewelry, and heels; whereas at an informal daytime reception, luncheon, or seminar, they will wear more subdued dresses or suits. When in doubt, never hesitate to ask your hostess what she plans to wear.
Next Slide: Casual