Yes, MINORITIES is a Scrabble word!

Letter values in Scrabble US: M 3, I 1, N 1, O 1, R 1, I 1, T 1, I 1, E 1, S 1.

Is it a valid word?

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

a group of people who differ racially or politically from a larger group of which it is a part
being or relating to the smaller in number of two parts
any age prior to the legal age