Etymology

The (early) OE form byrne will not account for the variant forms first met in late OE either in respect of initial br- without metathesis or of the second syllable with /j/ (late OE <brynige> etc.) or /i/ (e.g. ME <bruny>); this latter feature implies an earlier formation of the type *brunj- which ought to have resulted in an OE form with gemination (*brynne; see also SPS 62). Some influence from ON, cp. OIcel brynja ‘cuirass, hauberk, coat of chain mail’ (and cp. further Go brunjō, OS brunnia, OHG brunnia, brunna), is usually therefore cited. The ulterior etymology of the word is unclear. However it is difficult in the case of ME variants in <u> (as opposed to reflexes certainly continuing a late OE /y/, which strongly imply Scandinavian input) to rule out some influence from medieval Fr brunie, bronie etc. (cp. also MLat brunia, bronia).

PGmc Ancestor

*brunjon-

Proposed ON Etymon (OIcel representative)

brynja ‘cuirass, hauberk, coat of chain mail’ 
(ONP brynja (1) (sb.))

Other Scandinavian Reflexes

Far brynja, Icel brynja, Norw brynje, ODan brynje, OSw brynia, brönia

OE Cognate

byrne 'corslet'

Phonological and morphological markers

[

absence of metathesis

] (possibly diagnostic)

Summary category

C2

(C1a)

Attestation

There are several occurrences of br- forms in late OE, inc. in charters associated with EAngl (see SPS 284, DOE, Peters 95).  Very common and widespread in ME, though in the later period mainly found in alliterative verse (see McGee 498–9, who regards its distribution in manuscripts of SJ as showing a N bias).

Occurrences in the Gersum Corpus

Gaw 580, 861, 2012 etc.; WA 1247, 1295, 2214 etc.

Bibliography

MED brinie (n.) , OED brinie, brynie (n.) , HTOED , Dance bruny, Bj. 183-4, SPS 62–3, 284, de Vries brynja, Mag. brynja, Bj-L. brynje, Orel *ƀrunjōn, Kroonen *brunjōn-, AEW brynige, byrne, DOE brynige, byrne