Pondering the Proper Plural of "Peplum"

I am, let it be known, a sucker for a peplum. Probably from the time i was a girl, and there was one of those tiny little illustrations beside the definition for "peplum" in the Webster's Collegiate Dictionary i borrowed from my father when doing my homework... (i am also one of those folks who can get lost reading a dictionary like a novel, which is probably why i remember stumbling across "peplum," instead of some more likely vocabulary word).

I just though it looked so cool, and was dismayed that they didn't crop up on the clothes i saw around me. Now, i know that this problem can be solved through the wonder of vintage patterns. A few photos for your inspiration, all from 1940s patterns: