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.
Formal attire is clothing that is appropriate for extremely formal events, such as weddings, dances, and other special occasions. This type of attire can generally be broken into two categories: white tie and black tie. Determining what to wear to a formal event also depends on the time of day and context of the event.