The Collaborative International Dictionary of English v.0.48:

Rolodex \Rol"o*dex\ (r[^o]l"[-o]*d[e^]ks), a. [Trade Mark of
   Newell Office Products.]
   A trade name for a type of card file; as, a Rolodex(R) card
   file. Also used informally and improperly as a noun meaning
   Rolodex(R) card file.
   [PJC]