index [LME] In Latin index meant ‘forefinger, informer, sign’, Its second part is related to dicare ‘to make known’, also the source of indicate [E17th] and related words. The earliest uses in English refer to the finger that we would now usually call the index finger. Because this finger is used for pointing, index came to mean ‘a pointer’, either a physical one or some piece of knowledge that points to a fact or conclusion—a pointing finger was sometimes added to the margin of manuscripts to draw the reader’s attention to a particular topic. And because a list of topics in a book points to their location in the text, publishers and scholars gave such a list the name index in the late 16th century.