Clothing foreign trade: is the English of split swimsuit Tankini or Seperate?

First of all: two-piece swimsuit,

Corresponding: One-piece swimsuit.

Then let's look at two words you said:

The definition of "panties" is "a two-piece swimsuit consisting of a vest and a bikini bottom".

However, the definition of "single" as a noun is "things that make up their units, in particles"

By definition, "Tankini" is the most suitable.

Looking at the practical application, the split swimsuit also uses "Tankini": for example,

Tanchini in Blanca and Tanchini in jean paul gaultier.

So the English translation of "split swimsuit" is "Tankini".

I hope I can help you. Please also adopt it, thank you!