Yes, STABILIZER is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, A 1, B 3, I 1, L 1, I 1, Z 10, E 1, R 1.

Is it a valid word?

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

a chemical that is added to a solution or mixture or suspension to maintain it in a stable or unchanging state
airfoil consisting of a device for stabilizing an aircraft
a device for making something stable

Not playable in Scrabble US: STABILISER.