Note † — II. THE FIGHT AT FINNSBURH:
Reading edition
l. 1675. ondrǣdan. "In late texts the final n of the preposition on is frequently lost when it occurs in a compound word or stereotyped phrase, and the prefix then appears as a: abútan, amang, aweg, aright, adr'ǣdan."—Cook's Sievers' Gram., p. 98.