Yes, ABNORMALITY is a Scrabble word!

Letter values in Scrabble US: A 1, B 3, N 1, O 1, R 1, M 3, A 1, L 1, I 1, T 1, Y 4.

Is it a valid word?

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

an abnormal physical condition resulting from defective genes or developmental deficiencies
retardation sufficient to fall outside the normal range of intelligence
marked strangeness as a consequence of being abnormal
behavior that breaches the rule or etiquette or custom or morality

Also: mental defectiveness.

Not playable in Scrabble US: ABNORMALCY.