According to fashion experts at the Global Post, a semiformal event requires dark suits for men and cocktail dresses for women. Attire for semiformal office parties should be conservative, while evening semiformal events allow the addition of dressy accessories.
Semiformal is a broad attire recommendation for an event. It ranges from clothing that is slightly dressier than business wear to outfits just below the level of formal wear. Although dark suits are required for men, festive colored shirts and playful ties are acceptable for all but the most conservative venues. Women can start with a little black dress or other suitable cocktail dress and add accessories in line with the tone and theme of the event.