Yes, INDICES is a Scrabble word!

Letter values in Scrabble US: I 1, N 1, D 2, I 1, C 3, E 1, S 1.

Is it a valid word?

INDICES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a numerical scale used to compare variables with one another or with some reference number
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
a mathematical notation indicating the number of times a quantity is multiplied by itself
an alphabetical listing of names and topics along with page numbers where they are discussed
the finger next to the thumb

Also: index number, index finger.