Yes, ROUNDWORM is a Scrabble word!

Letter values in Scrabble US: R 1, O 1, U 1, N 1, D 2, W 4, O 1, R 1, M 3.

Is it a valid word?

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

infections of the skin or nails caused by fungi and appearing as itching circular patches
unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

Also: nematode worm.