Yes, GENERALISATION is a Scrabble word!

Letter values in Scrabble US: G 2, E 1, N 1, E 1, R 1, A 1, L 1, I 1, S 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

an idea or conclusion having general application
the process of formulating general concepts by abstracting common properties of instances
reasoning from detailed facts to general principles
(psychology) transfer of a response learned to one stimulus to a similar stimulus

Also: inductive reasoning, stimulus generalization, stimulus generalisation.