A large sheet of fabric worn around the waist as a skirt, usually over a bikini. It's usually tied into a knot at one side of the hip.
The Japanese word for sarong is パレオ (pareo). Technically, a pareo and a sarong are different garments: the former originates in Tahiti, the latter in Malaysia. In their traditional, native forms they might be distinguished. However they are usually equivalent in common usage.