Pajama cover-up is a term used to describe clothing items that are worn over pajamas. The two most common items used for this purpose are bathrobes and robes. A BATHROBE is an item of clothing that is typically made of absorbent material and is worn after bathing or swimming. A ROBE is a loose-fitting outer garment that is usually knee-length or longer. Both bathrobes and robes can be used as a pajama cover-up.