From The Free Dictionary:
n. pl. pep·lums
1. A short overskirt or ruffle attached at the waistline of a jacket, blouse, or dress.
2. See peplos.
[Latin, robe of state, from Greek peplon, neuter of peplos, peplos.]
And a wikipedia article on the Greek peplos garment: http://en.wikipedia.org/wiki/Peplos (with amusing and potentially nsfw diagrams.)
This week definitely has a word. I bought the jacket on the left at a used clothing store this week, and found out it was probably the Peplum Jacket from J. Crew. That had me wondering what that word was all about, and now I know. It occurred to me I'm often looking up this type of stuff, so maybe I ought to share it on my blog sometimes. Weekly, hopefully.