Blackcoats are typically associated with formal attire worn by professionals, such as lawyers or judges. However, there are several antonyms to blackcoats that may be used to describe different types of clothing. One antonym for blackcoats is casual attire such as t-shirts or shorts. Another antonym could be colorful apparel such as a bright red or yellow dress. Outerwear such as jackets, sweaters, or vests could also be used as antonyms to blackcoats. Additionally, sportswear or uniforms worn for a particular activity or occupation could serve as antonyms to blackcoats. Ultimately, the antonym for blackcoats depends on the context in which it is being used.