Is “Mightiest” a Scrabble word?
Yes
MIGHTIEST
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 Mightiest
adjective
1.Very strong; possessing might.
“He's a mighty wrestler, but you are faster than him.”
2.Very heavy and powerful.
“He gave the ball a mighty hit.”
3.Very large; hefty.