A bikini is usually a women's abbreviated two-piece swimsuit with a bra top for the chest and panties cut below the navel. The basic design is simple: two triangles of fabric on top cover the woman's breasts and two triangles of fabric on the bottom cover the groin in front and the buttocks in back. The size of a bikini bottom can range from full pelvic coverage to a revealing thong or G-string design.

The BIKINI state was an alert state indicator previously used by the UK Ministry of Defence to warn of non-specific forms of threat, including civil disorder, terrorism or war. Signs giving the current alert state were displayed at the entrance to government buildings and military installations. It was established on 19 May 1970. According to the Ministry of Defence, the word bikini was randomly selected by a computer.