Yes, LAZINESSES is a Scrabble word!

Letter values in Scrabble US: L 1, A 1, Z 10, I 1, N 1, E 1, S 1, S 1, E 1, S 1.

Is it a valid word?

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

inactivity resulting from a dislike of work
relaxed and easy activity
apathy and inactivity in the practice of virtue (personified as one of the deadly sins)