Yes, COALITIONS is a Scrabble word!

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

Is it a valid word?

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

an organization of people (or countries) involved in a pact or treaty
the state of being combined into one body
the union of diverse things into one body or form or group; the growing together of parts

Not playable in Scrabble US: COALESCENCY.