If you're planning a party, do your guests a favor and keep the lingo for the dress code standard. Don't use terms like "festive" without something following it like "cocktail". Don't be vague and say "Fabulous" or create your own term that only your friends know like "L.A. Formal". There are only a few descriptions you need. Here I've listed the dress code standards for Women. Feel free to send me a note or comment if you have specific questions or want to send a pic to see if what you're planning is acceptable!
BLACK TIE: Can be floor-length or tea length. Mini dresses or skirts are not appropriate. Color and beading is acceptable, as well as tasteful sequins.