A tankini is a type of two-piece swimsuit. The tankini is disguished from the classic bikini by the difference in tops. The tankini top extends downward to somewhere between just above the navel and the top of the hips. This type of swimwear is considered by some to provide modesty closer to a one piece suit with the convenience of a two piece suit, e.g. the entire suit need not be removed in order to go to the bathroom. Tankinis come in a variety of styles colors and shapes, some include features such as integrated push-up bras.

A tankini for pregant women also exists, which is divided in front exposing the navel. It is named the "peekaboo tankini".

For information about the tankini please visit Wikipedia. Note: the above defination was from Wikipedia as well.