Is “Mossback” a Scrabble word?
Yes
MOSSBACK
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Mossback
noun
1.A turtle that, because of its age, has a growth of algae on its back.
2.An old fish.
3.(by extension) A very conservative or reactionary person, especially one with old-fashioned views.