v1.0
Publishing history:
v1.0: 19/03/26
òs m. [ɔːs̪], 
Disyllabic *òthas [ɔ:əs] was recorded for Harris (Faclan bhon t-Sluagh˄).
Henderson (1910, 215) notes radical plural forms in both òis and òsan.
MacBain (1896, 1911); Mackay (1897, 94: SG os < Ice. oss [sic]); Henderson (1910, 215); Bugge (1912, 305); Marstrander (1915a, 125); Christiansen (1938, 5, 25; so also de Vries 1962); MacLennan (1925; so also Stewart 2004, 411); Oftedal (1980, 173); Cox (1991, 492; 2002a, 80); and McDonald (2009, 391).
Bugge (1912, 305) also derives O’Reilly’s (1817; 1864) Irish dictionary’s os [leg. ós 
Cf. Dinneen 1927 and Ó Dónaill 1977, s.v. ós.
Christiansen (1938, 25) incorrectly interprets Marstrander’s position as doubting SG òs derives from ON óss.
eDIL˄ cites Bugge as deriving EG ós from ON hóss [sic], and appears to imply (incorrectly) that Marstrander concurs.
McDonald (2009, 391) cites MacBain’s (1895, 235) discussion of Old Norse loan-names in Gaelic containing ON óss, 
E.g. SG Barbhas (Eng. Barvas), for which see Cox 2022, 501–06.
For examples from Lewis, cf. Cox 2022a, 219, 266, 319. In South Uist, cf. (OS 1843–82) Loch an Ose NF787456 and Rudh’ an Ose ‘the promontory of the outlet’ NF779450. Note that Taylor (2011) lists the Gaelic form for Noss Head in Caithness ND386549 as Rubha Nòis, which he takes to be a contraction of *Rubha an Òis ‘the headland of the river mouth’, although a suitable river mouth seems lacking. However, Noss Head (Ortelius 1592a: Nose head; Blaeu 1654: Noss), despite a suggestion that it derives from ON snǫs f. ‘projecting rock’ (Northern Lighthouse Board), may go back to MScots nos(e) ‘the nose of a person or animal’ (< early MEng. nos(e) (DOST˄)), if not to Scots (Shetland) nos ‘a rocky point, tongue of land; (properly) nose’ (< ON nǫs f. (Jakobsen 1928; SND˄, s.v. noss)). (For Ortelius’s (1592b) Berubium prom. (for Verubium Promontorium), see Watson 1926, 36, and Breeze 2004 and 2007.)
It may be that SG òs has influenced the development of Scots noust ‘boat-dock’ as SG nòs, q.v.