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.
For women, semi-formal attire is somewhat flexible. Women can wear a dress, pant suit or dress suit. Preferred fabrics for semi-formal attire for women include silk, velvet, rayon, cashmere, high quality polyester brocades, or velour. Usually, anything silky goes.