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A dictionary with thumb indexes (on the right).

A thumb index, also called a cut-in index[1] or an index notch[2], is a round cut-out in the pages of dictionaries, encyclopedias, Bibles and other large religious books, and various sectioned, often alphabetic, reference works, used to locate entries starting at a particular letter or section. The individual notches are called thumb cuts.

See alsoEdit


  1. ^ "thumb index". Bookbinding and the Conservation of Books: A Dictionary of Descriptive Terminology. Foundation of the American Institute for Conservation. Retrieved 8 May 2012.
  2. ^ Popular Mechanics, September 1956, page 184, (web link)