thumb index

¹

noun

1. a series of labeled notches cut along the fore edge of a book, to indicate the divisions or sections.

thumb-index

²

[thuhm-in-deks]

verb (used with object)

1. to provide (a book) with a thumb index.

thumb index

noun

1. a series of indentations cut into the fore edge of a book to facilitate quick reference

verb

1. (tr) to furnish with a thumb index

Word History and Origins

Origin of thumb index¹

First recorded in 1900–05