Publishing history:v1.0
v1.0: 13/10/25
nòs m. [ᵰ̪ɔ̃ːs̪], gen. nòis [ᵰ̪ɔ̃ːʃ], ‘boat-dock, boat-noust’ is said by Matheson (1948, 66–67) to derive almost certainly from ON naust nt. ‘boat-house, boat-shed’. Matheson notes that the word occurs in two 17th-century poems: in ‘A’ Chnò Shamhna’ by Eachann Bacach (Mull, ?c. 1600–post-1650): g’a stiùireadh gu nòs ‘to guide it to harbour’ (Ó Baoill 1979, 14–25: 24.275), and in the genitive in ‘Sgeul an Eibhneis’ by Iain mac Ailein (Mull, c. post-1650–pre-1745): gu tearuinteachd nòis (Sinclair 1888, 57–59: 59.11) ‘to the safety of harbour’. Further, the word occurs with the genitive of luingeas ‘ship’ in MacDomhnuill 1741 (p. 312 [leg. 112]: nós luingais ‘a dock for ships’), Shaw 1780 (nos luingas ‘ship-dock’) and Armstrong 1825 (s.v. nòs: nòs luingeis ‘ship-dock’); Dwelly (1911) cites Armstrong’s nòs luingeis, but also the form nòs-luinge, with the genitive of long ‘ship’, supplied by Angus Henderson (Ardnamurchan, 1866–1937).
More recently, SG nòs is recorded for Stoer, West Sutherland (Faclan bhon t-Sluagh: 
Whose informant connects the word with ON noust [sic].
So AFB˄: nòs and òs ‘naust [sic]’, Skye.
ON naust yields Scots noust [nɔust] (also (Shetland) nust [nust]) (SND˄). ON naust would be expected to yield SG *nòst *[ᵰ̪ɔ̃ːs̪t̪] regularly, cf. ON baunir pl. ‘beans’ ⇒ SG pònair, q.v.; Scots noust might also yield SG *nòst, cf. Scots knoud [nʌud] ‘gurnard’, a reduced form from SG cnòdan, q.v., although SG *nobhst *[ᵰ̪ɔus̪t̪], *[ᵰ̪ʌus̪t̪] might be a possible outcome, cf. Scots bouster [ˈbʌustər] (bolstar) > SG bobhstair. In either event, SG *nòst yielding SG nòs, with loss of t, is unexpected. Loss of inital n- in SG òmhs, on the other hand, is paralleled (if only coincidentally) in the Scots (Caithness) form oast (recorded in 1934 (SND˄, s.v. noust)); cf. similar aphesis in Scots owdan < *knoudan, through mistaken division after the indefinite article (< SG cnòdan, above). However, the development nòs > òmhs, with its ‘independent’ nasality (Ó Maolalaigh 2003a, 112–13), may have taken place within Gaelic itself, independently of the development noust > oast in Scots; cf. SG uimhir ‘amount, number’ < EG nuiṁir < Lat. numerus. Yet the apparent restriction of the distribution of SG nòs and its variants to the Inner Hebrides and the Western seaboard may favour a Scots over an Old Norse provenance.
In addition to the references to Mull, Tiree, Ardnamurchan, Skye and Stoer, above, Shaw (1780) was from Arran, and MacDomhnuill’s (1741) word list generally reflects the Gaelic of Moidart and its environs.
While SG nòs etc. from ON naust seems on balance less likely than a derivation from Scots noust, a derivation from the latter remains problematic, and it might be worth considering whether there has been conflation between Scots noust and SG (an) òs, i.e. the dative Gaelic article + SG òs ‘outlet’, q.v., e.g. (with the preposition meaning ‘to, into’) don òs/dhan òs, yielding nòs, nòsa and òmhs, according to dialect. For the Skye variant òmhas < òmhs, cf. SG *òthas (Faclan bhon t-Sluagh˄, s.v. òs: [ɔ:əs], Harris) < òs.