Yes, DEMOTIC is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, M 3, O 1, T 1, I 1, C 3.

Is it a valid word?

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

of or written in or belonging to the form of modern Greek based on colloquial use
of or for the common people

Also: demotic script.

Not playable in Scrabble US: ROMAIC.