Yes, INHIBITION is a Scrabble word!

Letter values in Scrabble US: I 1, N 1, H 4, I 1, B 3, I 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

(psychology) the conscious exclusion of unacceptable thoughts or desires
the quality of being inhibited
(physiology) the process whereby nerves can retard or prevent the functioning of an organ or part
the action of prohibiting or inhibiting or forbidding (or an instance thereof)