I think this type of garment was referred to as a playsuit (and often was actually a swimsuit) I think the "skirt" was actually split, like shorts, or perhaps a short skirt covering matching panties.
Some similar outfits are here: http://www.sovintagepatterns.com/page/page/2871951.htm
, especially this one: http://www.sovintagepatterns.com/catalog/item/2871951/5750940.htm
, though without the halter top.
I think my mother had some of these when I was a kid.