A onesie is a one-piece, t-shirt-like baby garment that has snaps at the crotch to keep it from riding up and exposing the baby's tummy. Onesies are also called bodysuits. The term "onesie" is most often used to describe a short-sleeved bodysuit that does not cover the baby's legs, but it also can refer to versions with long sleeves and long legs. Onesies can be used as a complete outfit, as a t-shirt, or as an undergarment. Onesies range in style from simple, white, undergarment versions to colorful, patterned and embroidered types.