v1.0
Published 01/10/24
1bàgh m. [b̥aːɣ], gen. [b̥aːj], 
Oftedal 1956, 103: /bɑːɣ/; 1972, 116: [baːɣ]; Cox 1992, 139: [b̥aːɣ].
‘bay’. MacBain (1911, 26) derives this word from Eng. bay (itself from Fr. baie < Lat. baia (OED˄)), although MacLennan (1925) derives it directly from Fr. baie. On the other hand, Wentworth (2003, s.v. bay) takes the word SG (Gairloch) beidhe [b̥e.e] to be ‘doubtless from Eng. bay’. For bàgh, Goodrich-Freer (1900, 67–68) proposes a derivation from ON bugr m. (leg. bug acc.) ‘bend, curve’ (although ON u could not formally yield SG [aː]) and rejects the derivation from ON vágr m. ‘bay’ suggested by Fr Allan McDonald. Roderick McDonald (≈2009, s.v. vágr) sees ‘nothing to necessarily favour English over Old Norse [vágr] as the source, [but] the presence in place-names 
Citing SG Stéornobhágh, leg. Steòrnabhagh (Cox 2022, 898–902).
supports Old Norse’. The point about place-names is moot and a development of ON vág acc. *[ʋɑːɣ] to SG bàgh [b̥aːɣ], with delenition of the initial fricative via back-formation in Gaelic, is regular. This is supported by Craigie (1894, 162), Mackenzie (1910, 383), Oftedal 1956, 103, 1962, 120, 122, 1972, 116, 1980, 172, and Cox 1991, 492, 1992, 138–139, 2022, 146, 204, 216.
MacBain (1911) derives Ir. bádh (Dinneen 1947: bádh m., báighe f.; Ó Dónaill 1977: bá f., báigh f.) 
E.g. Wagner 1979, 203: an bháighe [ə wɑːijə]; Mckay 2007, 131: Báighe na nDúnaibh (formerly Cuan na gCaorach); dúchas.ie˄, s.v. Báḋ Baoi (Bunachar Logainmeacha na hÉireann˄: Bá Bheanntraí), Eng. Bantry Bay.
from Eng. bay, 
Professor Seòsamh Watson (pers. comm.) suggests northern báigh(e) and southern bá are from Eng. bay or perhaps Fr. baie, with bá a back-formation from a dative form, cf. pádh ~ páighe ~ pághaidh ‘pay’ (Dinneen 1947).
while Broderick derives Mx baie 
PNIM I, 23, IV, 169: [bai], 221: [bɛi], VI, 355–56: [bɛːi], [ba-i], [bei], 514: [beːi].
from ON vág 
PNIM IV, 169, VI, 355–56, 529. So also Ó Muirithe (2010).
and compares SG bàgh 
PNIM VI, 355–56.
or an oblique case form of it (SG bàigh gen.
Broderick 1984 II, s.v. baie; PNIM I, 23, IV, 221.
).