Other forms: Rolodexes
A Rolodex is an old-fashioned desktop organizational system, a contact list stored in a rotating card file. To find a phone number in a Rolodex, you turn a dial and flip through cards to find the contact's name.
There are still offices that rely on a Rolodex to keep track of names, numbers, and addresses. These physical devices contain cards with typed or handwritten contact information, organized alphabetically around a central tube that's manually controlled by a knob. These days, people sometimes use the term figuratively to describe a person who's extremely good at keeping track of information. Invented in 1956, the Rolodex got its name from the words rolling and index.