Yes, OPENNESSES is a Scrabble word!

Letter values in Scrabble US: O 1, P 3, E 1, N 1, N 1, E 1, S 1, S 1, E 1, S 1.

Is it a valid word?

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

without obstructions to passage or view
characterized by an attitude of ready accessibility (especially about one's actions or purposes); without concealment; not secretive
willingness or readiness to receive (especially impressions or ideas)