monokini
In modern terminology, a monokini is a type of one-piece swimsuit where the swimsuit is only connected in the front by the conjoining swimsuit. In detail, there are large cutouts around the sides and generally less coverage from the back. It's a more aesthetic look to the one-piece swimsuit being a combination to that of a bikini and one-piece.
The earliest term of monokini originates in the mid-1960s, designed by Rudi Gernreich, where it was first introduced as a topless swimsuit with two shoulder straps. This term has since became obsolete in the later years, but some modern topless monokini still exist alongside the one-piece monokinis.