Yes, TRANSPIRATIONS is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, A 1, N 1, S 1, P 3, I 1, R 1, A 1, T 1, I 1, O 1, N 1, S 1.

Is it a valid word?

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

the passage of gases through fine tubes because of differences in pressure or temperature
the process of giving off or exhaling water vapor through the skin or mucous membranes
the emission of water vapor from the leaves of plants