definition -A woman who has been accepted to star in a play, Music video(most of the times), or television show not for her preforming prowess, Aesthetic appearance, or even sparkling personality but, for the size & bounciness of her ass to use usually as a distraction from how bad said play, video, or show is or to just attempt to be sexy.
The very beginning of Pitbull's Hotel Room Service music video couldn't be a more perfect example of a asstress.
Man 1: *is watching a booty filled show* Man there is some great actresses in this show.
*a 2nd man hears Man 1 & enters the room*
Man 2: *looks at show* no it don't. All they doing is shaking ass. They ain't actresses they are ASStresses.