- Potent, effective, tough; having much power.
- c. 1200, Þe Liflade ant te Passiun of Seinte Margarete:
- Ah leve ȝe, Ich reade oƿ, o þe liviende Godd, mihti ant meinful ant euch godes ful, þe hereð þeo þe Him cleopieð to, ant heovene-ȝetes openeð!
- But believe, you, I advise you, in the living God, mighty and powerful and full of all good, who hears all who call to him, and the gates of heaven will open!
- (rare) Shining, light; having much brightness.
- English: mainful