Yes, ABSOLUTISMS is a Scrabble word!

Letter values in Scrabble US: A 1, B 3, S 1, O 1, L 1, U 1, T 1, I 1, S 1, M 3, S 1.

Is it a valid word?

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

dominance through threat of punishment and violence
a form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)
the principle of complete and unrestricted power in government
the doctrine of an absolute being

Also: authoritarianism, one-man rule.

Not playable in Scrabble US: STALINISM.