Yes, MAJAGUAS is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, J 8, A 1, G 2, U 1, A 1, S 1.

Is it a valid word?

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

shrubby tree widely distributed along tropical shores; yields a light tough wood used for canoe outriggers and a fiber used for cordage and caulk; often cultivated for ornament
erect forest tree of Cuba and Jamaica having variably hairy leaves and orange-yellow or orange-red flowers; yields a moderately dense timber for cabinetwork and gunstocks

Also: hibiscus tiliaceus, cuban bast, blue mahoe, hibiscus elatus.

Not playable in Scrabble US: MAHAGUA, BALIBAGO, PURAU.