index

Where does the word "index" come from? It comes from Latin index, and was adopted directly into English (1500s).

Index’s story begins in Latin: index meant “forefinger, pointer.” From 'indicare', to point out; 'index finger' preserves the sense. It reached English by 1500s as index. A list of topics at the back of a book; the Church's Index of forbidden books began 1559. Today, index means an alphabetical list of topics in a book; an indicator.

1. Stage 1 · Latin · ancient index "forefinger, pointer", from 'indicare', to point out; 'index finger' preserves the sense.
2. Stage 2 · English · 1500s index "an alphabetical list", a list of topics at the back of a book; the Church's Index of forbidden books began 1559.