A catsuit is a one-piece form-fitting garment that covers the torso and the legs, and frequently the arms. They are usually made from stretchable material, such as lycra, chiffon, spandex, latex, or velour, but may use less elastic materials, such as leather or PVC. Catsuits frequently close by means of a zipper at the front or back. A catsuit is regarded as outerwear, but not normally street wear. Catsuits are also used for sexualization or other types of sexuality.

A unitard is a skintight, one-piece garment with long legs and sometimes long sleeves, usually stopping at the wrists and ankles. It differs from a leotard which does not have long legs. The leotard is also usually considered a more feminine clothing item, while the unitard is not. The garment can be thought of as a combination of a leotard and leggings, and was historically called a "one-piece long legged leotard". The term unitard is mostly used in relation to sports, while it is usually referred to as a catsuit in other contexts.