Yes, VOCALISM is a Scrabble word!

Letter values in Scrabble US: V 4, O 1, C 3, A 1, L 1, I 1, S 1, M 3.

Is it a valid word?

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

the system of vowels used in a particular language
the sound made by the vibration of vocal folds modified by the resonance of the vocal tract

Also: vowel system.

Not playable in Scrabble US: VOCALISATION.