Definition

Noun: A thumb index is a series of small, rounded cut-out sections or notches on the outer edge of the pages of a book. Each notch is labeled and corresponds to a different section or chapter, allowing the user to quickly find and open the book to that specific part by placing a thumb in the notch.

Usage

A thumb index is a practical feature found in reference books like dictionaries, encyclopedias, or manuals to facilitate rapid access to information. - The new edition of the dictionary includes a thumb index for each letter of the alphabet. - To find the chapter on verbs, use the thumb index marked 'V'.

Advanced Usage

• Design and Function: The effectiveness of a thumb index depends on the depth and spacing of the notches, as well as the clarity of the printed labels.
• Digital Analogy: In user interface design, the concept of a thumb index is sometimes used metaphorically to describe a navigational system with quick-access tabs.

Variants and Related Words

• Thumb tab: A similar feature, often a single protruding tab rather than a series of cut-out notches.
• Index: A more general term for an alphabetical list at the end of a book, or any system for finding information quickly.

Synonyms

• Ridge index
• Cut-in index
• Step index

Related Phrases

• To thumb through: To browse or look through a book quickly by flipping the pages with one's thumb. While related in action, this phrase describes the method of browsing, not the physical index feature itself.
  • She thumbed through the catalog to find the right product.

Noun

1. one of a series of rounded notches in the fore edge of a book to indicate sections