The phrase "in tails" is often associated with formal wear for men. However, there are many synonyms for this phrase that can be used to convey a similar meaning. One possible synonym is "in formal attire," which can describe any type of clothing that is considered appropriate for a formal occasion. Other synonyms include "in full dress," "in dress uniform," and "in evening wear." These phrases can be used to describe a variety of different formal outfits, such as military dress uniforms, tuxedos or suits, and evening gowns. Regardless of the specific synonym used, the overall meaning is clear: the person is dressed in a formal and often elegant manner.