Yes, COHESION is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, H 4, E 1, S 1, I 1, O 1, N 1.

Is it a valid word?

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

the state of cohering or sticking together
(botany) the process in some plants of parts growing together that are usually separate (such as petals)
(physics) the intermolecular force that holds together the molecules in a solid or liquid