A bodysuit is a one-piece form-fitting or skin-tight garment that covers the torso and the crotch, and sometimes the legs, hands, and feet, and cannot be used as a swimsuit. The style of a basic bodysuit is similar to a one-piece swimsuit and a leotard, though the materials may vary. A bodysuit, unlike a swimsuit or leotard, has snaps, hooks or velcro at the crotch. Thong or T-front thong bodysuits usually have the crotch opening moved up to the front to underbelly area to increase the wearer's comfort. A bodysuit may have sleeves and varying shoulder strap and collar styles. Bodysuits can be made from a number of fabrics, including cotton, lace, nylon, etc. In general, textile bodysuits include expandable fiber such as spandex for a better fit to the shape of the body.

A bodysuit is normally worn with trousers or a skirt. The top, torso part may act as a top for the smooth line it gives or because it cannot become untucked from trousers or skirt. They may also be worn generally by women as underwear, activewear, or foundation garments. Unlike a leotard, a bodysuit is not usually considered a form of athletic wear. Onesies (or snapsuits) are bodysuits for younger children, toddlers, and some adults that help keep diapers in place. The purpose of the opening at the crotch is to facilitate access to a baby's diaper or for a visit to the toilet.

There are also bodyshirts, like the counterpart to the bodysuit, they are loose-fitting garments that cover the whole torso, with sleeves in short to long lengths and crotch snaps. The difference is that they look like a shirt on the top portion of the garment, and may have a different stretch fabric in the waist to the crotch area to make them fit better. Cheerleaders also wear long sleeved crew neck and turtleneck bodysuits as part of their uniform.