The antonyms for the word "formals" are casuals or informals. Formals refer to clothing that is more dressy, typically worn to formal events such as weddings, proms, or galas. On the other hand, casuals or informals refer to clothing that is comfortable and relaxed which can be worn in everyday situations. This can include T-shirts, jeans, shorts or skirts. The difference in formals and casuals lies in their level of formality, where formals are more appropriate for formal events while casuals are more suitable for informal situations. So, when dressing up for a formal occasion, you may wear formals, whereas, for a casual hangout with friends, you may choose casuals to wear.