Is “Stiffen” a Scrabble word?
Yes
STIFFEN
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 Stiffen
/ˈstɪfən/
verb
1.To make stiff.
2.To become stiff.
Synonyms: starken