Yes, LIBERALISM is a Scrabble word!

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

Is it a valid word?

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

a political orientation that favors social progress by reform and by changing laws rather than by revolution
an economic theory advocating free competition and a self-regulating market