Yes, SYPHILIS is a Scrabble word!

Letter values in Scrabble US: S 1, Y 4, P 3, H 4, I 1, L 1, I 1, S 1.

Is it a valid word?

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

a common venereal disease caused by the treponema pallidum spirochete; symptoms change through progressive stages; can be congenital (transmitted through the placenta)

Also: lues venerea.