thong bikini
A bikini with a thong bottom. A thong bottom is a thin strip between the buttocks that leaves most of the butt cheeks bare.
Don't use this tag unless you can tell the bikini bottom leaves the butt cheeks bare. Most thong bikinis are also string bikinis, but not all string bikinis are thong bikinis.
Most micro bikinis are also thong bikinis due to their skimpiness.