Formal wedding attire sits between cocktail and black tie on the wedding dress code scale. It's slightly more elevated than cocktail attire and a touch less dressy than a black-tie nuptial. Formal wedding attire (synonymous with black-tie optional attire) offers more flexibility than black tie, so dressy separates and dresses that hit above the ankle are acceptable, as well as fitted, darker-hued suits paired with a crisp white button-down and tie.