Definition of insecure. 1  1 : not confident or sure : uncertain feeling somewhat insecure of his reception. 2  2 : not adequately guarded or sustained : unsafe an insecure investment. 3  3 : not firmly fastened or fixed : shaky the hinge is loose and insecure.
For men, semi-formal attire means wearing a full suit, with vest optional. A tie, either bow or straight, should be worn, and the shirt should be a simple button down. Suit fabric choices are primarily wool gabardine or cashmere. However, a wool blend will do.
Wedding invitations may request that guests dress in semi-formal attire. Some appropriate options for women include a cocktail dress (such as a little black dress), a dressy suit or a dressy skirt and top, taking into consideration the season. Men can't go wrong with a dark-colored business suit, a dress shirt, a tie, leather dress shoes and dark dress shoes. For a daytime semi-formal wedding, another appropriate option may be a stroller, which is an ensemble, usually dark gray, resembling a relaxed version of the morning dress style.