Yes, CONTRARIES is a Scrabble word!

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

Is it a valid word?

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

a relation of direct opposition
exact opposition
a logical relation such that two propositions are contraries if both cannot be true but both can be false