https://www.celebritycruises.com/faqs/faq-fragments/enjoying-your-cruise-fragments/dining-dress-code
Smart Casual attire is required for entry to main dining, specialty dining, and the Celebrity Theatre. Smart Casual means you look comfortable yet tasteful in a dress, skirt, long pants, or jean, and stylish top or button-down. Shorts and flip flops are not considered Smart Casual. Each itinerary features one to two "formal" nights we call Evening Chic. Evening Chic means you dress to impress, glamorous and sophisticated in your own way, with a cocktail dress, skirt, slacks, or designer jean, an elegant dress top or blazer—some guests even pack a tuxedo or gown for onboard photos. The Daily program, delivered to your stateroom and available at the Guest Relations Desk, will be your guide to the correct attire each evening. If you do not wish to participate in Evening Chic, Smart Casual attire is acceptable for dining and theater.
Most nights, Smart Casual attire is appropriate for dinner in the Main Dining Room(s). For 6 night cruises or less, there will be 1 Evening Chic night where women should feel comfortable in cocktail dresses, skirts, pants or designer jeans with an elegant top. Men should feel comfortable in pants, designer jeans, long sleeved or button-down shirt, sweaters, sport coats or blazers. For 7 night cruises or longer, there will be two (2) Evening Chic nights.
For 6 night cruises or less, there will be 1 Evening Chic night per cruise. For 7 nights or longer, there will be 2 Evening Chic nights while onboard. While Tuxedos and Formal attire is still appropriate, they are not required and guests will feel comfortable in both formal wear and a dressier smart casual style. Jackets are not required.