History: Bikini In 1940-50's

Types of underwear worn by both men and women are identified as bikini underwear, similar in size and revealing nature to the bottom half of a bikini bathing suit. For women, bikini underwear can refer to virtually any tight, skimpy, or revealing undergarment that provides less coverage to the midsection than traditional underwear, panties or knickers. For men, a bikini is a type of undergarment that is smaller and more revealing than men's briefs.
Sports bikini
There is evidence of ancient Roman women playing Expulsim Ludere, an early version of handball. Female athletes who play beach volleyball professionally usually wear two-pieces. These bikinis are designed with functionality rather than fashion in mind.