A-butan

According to the Old English Dictionary:

-bflton;

a-butan

adv. ABOUT ; circa :-- Besæt ðone castel abútan beset the castle about, Chr. 1088; Th. i. 357, 29. Besǽton íone castel abúton they beset the castle about, Chr. 1090; Th. i. 358, 25. a-butan