Yes, indices is a Scrabble word!

Noun

1. A numerical scale used to compare variables with one another or with some reference number

2. A number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time

3. A mathematical notation indicating the number of times a quantity is multiplied by itself

4. An alphabetical listing of names and topics along with page numbers where they are discussed

5. The finger next to the thumb