thumb index

noun

A series of alphabetically marked or otherwise labelled semicircular cut-outs in the fore edge of a large reference book, encyclopaedia, Bible, etc., that allows quick access to various parts of the text.

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Meanings

nounthumb index (plural thumb indexes)

plural thumb indexes

  1. A series of alphabetically marked or otherwise labelled semicircular cut-outs in the fore edge of a large reference book, encyclopaedia, Bible, etc., that allows quick access to various parts of the text.
Cite this entry
APA

thumb index. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/thumb%20index

MLA

“thumb index.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/thumb%20index. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “thumb index,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/thumb%20index.

Source: thumb index on Wiktionary, CC BY-SA 4.0.