Thumb index

{{Short description|Round cut-out in the pages of a publication}}

{{Distinguish|edge index}}

File:Blacks-Law-Dictionary.jpg

A thumb index, also called a cut-in index{{cite web|title=thumb index|url=http://cool.conservation-us.org/don/dt/dt3508.html|work=Bookbinding and the Conservation of Books: A Dictionary of Descriptive Terminology|publisher=Foundation of the American Institute for Conservation|accessdate=8 May 2012}} or an index notch,{{Cite book |url=https://books.google.com/books?id=peEDAAAAMBAJ&dq=%22index+notches%22+in+reference+books&pg=PA184 |title=Popular Mechanics |date=Sep 1956 |publisher=Hearst Magazines |page=184 |language=en}} 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.

Several ways to achieve this indexing effect were invented and patented in the 1970s by Arthur S. Friedman, a printing engineer in New York.{{Cite web |title=Google Patents |url=https://patents.google.com/?inventor=Arthur+S+Friedman&before=priority:19790101&after=priority:19690101 |website=patents.google.com}}