Yes, ILLATION is a Scrabble word!

Letter values in Scrabble US: I 1, L 1, L 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation