"In late texts the final n of the preposition on is
frequently lost when it occurs in a compound word or phrase,
and the prefix then appears as a: abútan, amang, aweg, aright,
adr'ǣdan.
frequently lost when it occurs in a compound word or phrase,
and the prefix then appears as a: abútan, amang, aweg, aright,
adr'ǣdan.
Beowulf