Generally, no; adult guests are prohibited from wearing wedding dresses or "floor-length gowns" inside the theme parks during normal operating hours. Disney's attire policy strictly forbids costumes or clothing that drags on the ground for guests aged 14 and older, primarily for safety reasons (tripping hazards) and to prevent guests from being mistaken for official Disney characters. If you show up at the gate in a full bridal gown, security will likely deny you entry. The only major exceptions are for guests participating in a sanctioned Disney Fairy Tale Wedding event or for private, pre-arranged portrait sessions that occur before the parks open. For a regular park day, "Disneybounding" in a white sundress or wearing a bridal-themed t-shirt and ears is the accepted way to celebrate.