I think that the definition could go anywhere from very *unoffensive* swimsuit, where there is exposure - gasp!! - of feminine (blush, blush) ankles-- to Playboy's "Diet Lite" pseudo-nude semi-pornography. I sat "semi' because the model's actual bodies are hidden under pounds (kilos) of body paint.
Here is something to ponder: What about the work of Bette Page? There is a whole cult of afficianados that will argue -- and I'm not at all sure groundlessly -- that this work is *ART*!!