Definition of "alderbest"

That all the best archers of the north / Sholde come upon a day, / And he that shoteth alderbest / The game shall bere away.

Late 15th c. A Gest of Robyn Hode

That Lombard's nose mean I, / That standeth yet awry; / It was not healed alderbest, / It standeth somewhat on the west;

1522, John Skelton, Why Come Ye Nat to Courte?