v1.0
Published 01/10/24
diosg m. [d̥ʲis̪k], 
Cf. /dʲisg/ (AFB˄).
gen. idem, ‘dish, platter; disk (also in computing)’ (AFB˄) is derived by Mackay (1897, 95: diosc ‘a plate’, Skye) from Ice. diskr m. ‘plate’ (Cleasby 1874), cf. ON diskr 
Itself perhaps from OEng. disc ‘plate, bowl, platter’, < Lat. discus (OED˄).
m. ‘counter; dinner plate, dish’ (NO). Armstrong (1825: †diosg) derives the word from Lat. discus, so also MacBain (1911) and MacLennan (1925), while McDonald (2009, 349), although he considers a loan from Old Norse uncertain, sees no reason to prefer a Latin over an Old Norse provenance. However, there appears to be a degree of confusion over the form and meaning of the Scottish Gaelic word, and there may be some doubt over its status.
With a short stressed vowel, SG diosg in the sense ‘plate or dish’ is listed by Armstrong (1825: ‘plate, platter, dish’), HSS (1828: ‘dish’), MacLeod and Dewar (1839: ‘dish’), MacBain (1896; 1911: ‘dish’), and MacLennan (1925: ‘dish’), who also has the sense ‘quantity of water in a dish’. With a long stressed vowel, Dwelly (1911) lists dìosg in the senses ‘dish, plate, platter; any quantity of water or liquor in a dish; barren cow’, citing the contexts is bràthair do ’n dìosg an tuairnear ‘the turner is brother to the dish’ and chaidh am mart an dìosg ‘the cow has become dry’.
SG dìosg [d̥ʲiːs̪k], [d̥ʲiəs̪k] in the sense ‘barren cow’ goes back regularly to EG dísc ‘barren, dry, run dry’ < dí- an intensive prefix + sesc adj.‘dry, barren, unproductive’ (eDIL˄; Vendryes 1996).
SG diosg [d̥ʲis̪k] (MacLennan) and SG dìosg [d̥ʲiːs̪k] (Dwelly; also McDonald 1972: South Uist) in the sense ‘quantity of liquid’, assuming both are authentic, may be loan-shifts from Scots tweest ‘twist, a small amount of drink etc.’ (SND˄), with st ~ sg alternation, 
Cf. SG cost, cosg < Eng. cost; SG balaist ‘ballast’, ballaisg ‘boaster’, s.v. ballart.
falling together with dìosg vb ‘to creak, squeak; gnash’, although McDonald (ibid.) compares SG taosg ‘measureful of liquid’ (EG taesc ‘jet, spurt, flow’ (eDIL˄)).
Dwelly’s dìosg ‘dish’, with a lengthmark, is no doubt in error for diosg [d̥ʲis̪k], with a short vowel, the accompanying proverb going back via Nicolson (1881, 222) and Armstrong (1825) to Macintosh (1785, 140–41), who generally omits lengthmarks: is brathair do’n diosg an tuarn fhear (sic), which is interpreted as is bràthair don diosg an tuairnear ‘the turner is brother to the dish’. Macintosh’s source is unknown, and it seems to be assumed that ‘the turner is brother to the dish’ makes adequate sense: perhaps the equivalent of ‘they are two sides of the same coin, they are closely related though seemingly different’; 
This is apparently the sense understood in ‘Is brathair do’n diosg an tairnear’, agus is coltach ri cheile a tha sgeul Luigh Lamfada agus sgeul Chuchulainn (sic) (..., and L.L.’s story and C.’s story are similar) (Mac-Talla VIII, No. 7, 1899, p. 50, col. 1).
however, in the context of lathe-working and wood-turning, dìosg ‘squeak, squeal’ might be equally if not more fitting, the meaning of ‘the turner is brother to the squeak’ perhaps being ‘take the rough with the smooth, accept both the pleasant and unpleasant sides of life’.
SG diosg [d̥ʲis̪k] in the sense ‘dish’ goes back to EG desc f. ‘dish, paten’, from Lat. discus (eDIL˄), 
Cf. Ir. deasc, (Ulster) dasc (Dinneen 1947), teasc (Ó Dónaill 1977). Note that Armstrong (1825) implies an apparently otherwise unattested Irish form diosg.
although it has perhaps been influenced by modern Eng. disc, disk. In spite of HSS’s (1828) assertion that diosg in the sense ‘dish’ was in use in common speech, early evidence for the word seems limited and is perhaps restricted to this one, possibly misread proverb. Mackay’s (1897) listing from Skye, then, is unexpected. It conceivably represents an archaism – Armstrong (1825) marks the word as obsolete – or it may have been gleaned from A Collection of Gaelic Proverbs and Familiar Phrases (1881) itself, whose editor Alexander Nicolson was from Skye; at any rate, the word has since been revived (if not reborrowed directly from English) in order to accommodate more recent applications of the English word.