You've heard the term a million times, but would you know a sundress if you saw it? According to Webster's (yes, they've got a definition) it's a dress made of lightweight fabric that typically has a wide neck and thin straps. Okay, that leaves some room for interpretation, which in the world of fashion is a good thing. Take a gander below at our picks for sundresses that are grown up enough to call your own, loosely fit the definition and, as a bonus, are all under $50. Keep track of your favorites and you might even get them on clearance a couple weeks down the road.