Yes, FRICATIVE is a Scrabble word!

Letter values in Scrabble US: F 4, R 1, I 1, C 3, A 1, T 1, I 1, V 4, E 1.

Is it a valid word?

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

a continuant consonant produced by breath moving against a narrowing of the vocal tract

of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then')

Also: fricative consonant.