Is “Marcher” a Scrabble word?
Yes
MARCHER
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 Marcher
/ˈmɑːtʃə/
noun
1.An inhabitant of a march (border country); specifically, a marcher lord.
2.A border territory, a march (now only in (attributive) use).