Yes, COLLOQUIUM is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, L 1, L 1, O 1, Q 10, U 1, I 1, U 1, M 3.

Is it a valid word?

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

an academic meeting or seminar usually led by a different lecturer and on a different topic at each meeting
an address to an academic meeting or seminar