Glad rags, also known as fancy or formal clothing, can have several opposite meanings depending on the context. The words used to describe the opposite of glad rags change accordingly. If one wants to describe casual and comfortable clothes, antonyms like everyday wear or lounge wear can be used. Conversely, if one wants to describe old, worn-out clothing, antonyms like drab or shabby can be used. If one wants to describe plain and simple clothing, antonyms like basic or minimalist can be used. Similarly, if one wants to describe unfashionable or outdated clothing, antonyms like outdated or unfashionable can be used.