noun. Largish surgically-enhanced rackage.
Real citation: "Demi busts out her robo-dirigibles and thonged buttcheeks while she gyrates on a table for an understandably grateful Burt Reynolds."
(Mr. Skin's Skincyclopedia : The A-to-Z Guide to Finding Your Favorite Actresses Naked, page 387, 2005)
Made-up citation: "Larry David refers to robo-dirigibles as 'big chemical balls.' Neither term is mentioned in the Bible."