Yes, HEADWORDS is a Scrabble word!

Letter values in Scrabble US: H 4, E 1, A 1, D 2, W 4, O 1, R 1, D 2, S 1.

Is it a valid word?

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

a content word that can be qualified by a modifier
a word placed at the beginning of a line or paragraph (as in a dictionary entry)

Also: head word.