The tankini (a.k.a., the cropped tank) is actually the top residual of a maillot tank cropped at the base of the ribs. The result is a very full top, unlined and skin-hugging, and descending down toward the waistline (N198601). A tankini may be markedly similar to a croptop with the subtle differences including the details of the cut, the looseness, and the material (e.g., consider FI92801), and it has identical topology to the brassière.
Tankini usually contains no fasteners but it some cases it does have a zipper front, which can be partially unzipped of course (RP8812).
Tankini evolves during the late 1980s and is driven by two factors: Worn as a complement to culotte montante it closes bellage and compresses a narrow sliver of bare belly above (VE198610), at (M92596), or below (RP8509, RP8812) the navel. Secondly, tankini is stimulated by the emerging exercise wear, which adopts bikini silhouettes, but with stronger support (VE198610, M92596).
In fact, tankini is worn not only with montante, but also with tanga and tap pants, both of which constrain a narrow bellage; it is also spotted with nombril and v-kini (RP8812, RL9101-02), in which the brief moves belly-down in unison with the lowering top.
Tankini may also be a component of a miokini, in which a very full bodied top is attached to a culotte (e.g., FI8821).
Rolldown tankini and culotte montante. The tankini recovers the belly downward.