(in′deks) noun plural ·dex·es or ·di·ces (-də·sēz)
1. Anything used to indicate, point out, or guide, as the index finger, or forefinger, the hand of a clock, a pointer, etc.
2. Anything that manifests or denotes: an index of character.
3. An alphabetic list of matters or references, as in a book.
4. Math. An exponent.
5. A mark employed to direct attention.
6. A numerical expression of the ratio between one dimension or magnitude and another with which it is regarded as comparable: the cephalic index.
7. Obs. A prolog; prelude.
—v.t.
1. To provide with an index.
2. To enter in an index.
3. To indicate; mark. [<L. See INDICATE.]
—in′dex·er noun
—in·dex′i·cal adjective

(in′deks) noun
A list of interdicted books prepared by the Holy Office of the Roman Catholic Church. The Index Expurgatorius, no longer officially prepared, indicated those books which, with certain expurgations, might be read; the Index Librorum Prohibitorum, those which are forbidden.