S means small, which translates roughly to a women's size 4 to 6 in most brands.

Is size 6 considered small?

What Is a Size 6? Size charts vary across the world. But based on this women's clothing size conversion table, size 6 in the United States and Canada is considered small.

Is a size 6 midsize?

A relatively new term, there is no set in stone definition of what it represents but it is generally accepted that anyone who falls between a US size 6 to 14, is considered mid-size.