—adj. (mightier, mightiest)
1 powerful or strong, in body, mind, or influence.
2 massive, bulky.
3 colloq. great, considerable.
—adv. colloq. very (a mighty difficult task).
Derivatives:
mightily adv. mightiness n.
Etymology: OE mihtig (as MIGHT(2))
Useful english dictionary. 2012.