Yes, BOMBARDMENT is a Scrabble word!

Letter values in Scrabble US: B 3, O 1, M 3, B 3, A 1, R 1, D 2, M 3, E 1, N 1, T 1.

Is it a valid word?

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

the rapid and continuous delivery of linguistic communication (spoken or written)
the heavy fire of artillery to saturate an area rather than hit a specific target
the act (or an instance) of subjecting a body or substance to the impact of high-energy particles (as electrons or alpha rays)
an attack by dropping bombs

Also: barrage fire.