Frock/frɑːk/ Definition 1 of 3Pro Tip 1/3Fashion Term Frock is often used to describe a particular style of dress, not any dress. In vintage shops, you might find a frock with an old-fashioned elegance. Pro Tip 2/3Older Usage 'Frock' can sound old-fashioned; in modern contexts, 'dress' is more common. My grandmother calls all my dresses frocks. Pro Tip 3/3Formal Occasions Frock might be used for formal or special occasion dresses in contemporary use. She's shopping for a frock for the wedding.