Definition of card index in English English dictionary
A card index is a number of cards with information written on them which are arranged in a particular order, usually alphabetical, so that you can find the information you want easily. a box of cards that contain information about something and are arranged in order, especially the cards with book information on them in a library American Equivalent: card catalog
file of cards which contain references to separate items (arranged in a certain order)
An index card is a small card on which you can write information. Index cards are kept in a box, arranged in order. a small card for writing on, used especially in an index (2)