'edge, brim' (Modern English )
Proposed ON Etymon (OIcel representative)
barmr 'brim, rim'
(ONP barmr (sb.))
Other Scandinavian Reflexes
Icel barmur, Norw barm, Dan barm
bearm 'bosom, lap; place of containment, etc.'
Phonological and morphological markers
This is the only instance of the relevant sense; see further Discussion by text. Instances with the native sense are widespread in OE and ME.
Occurrences in the Gersum Corpus
MED instead reads the sense at WA 4812 as (3b) 'hollow at the base of a mountain' as an extension of 'lap, bosom, bed etc.' from OE bearm.