Yes, ZODIAC is a Scrabble word!

Letter values in Scrabble US: Z 10, O 1, D 2, I 1, A 1, C 3.

Is it a valid word?

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

a belt-shaped region in the heavens on either side to the ecliptic; divided into 12 constellations or signs for astrological purposes
(astrology) a circular diagram representing the 12 zodiacal constellations and showing their signs