Is “Posse” a Scrabble word?
Yes
POSSE
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 Posse
/ˈpɒ.si/
noun
1.A group or company of people, originally especially one having hostile intent; a throng, a crowd.
2.A group of people summoned to help law enforcement.
3.A search party.