Vintage or Antique
Retro:retro simply refers to anything that looks out of style for the current time period. This could be clothing that was popular in the late 1990's (not technically vintage, yet) or any new design that references designs or ideas of the past. This also seems to be somewhat interchangeable with the word, "vintage inspired." The 1970's are often referred to as "retro" although they are technically over 40 years old... which can be (in my eyes) considered "vintage."
Here's a dress I bought at Modcloth that is retro, or "vintage inspired."