Yes, LURIDNESS is a Scrabble word!

Letter values in Scrabble US: L 1, U 1, R 1, I 1, D 2, N 1, E 1, S 1, S 1.

Is it a valid word?

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

the journalistic use of subject matter that appeals to vulgar tastes
unnatural lack of color in the skin (as from bruising or sickness or emotional distress)
the quality of being ghastly

Not playable in Scrabble US: ACHROMASIA.