v1.0
Published 01/10/24
blanndaidh adj. [ˈb̥ɫ̪ãũᵰ̪d̪̥i] 
Cf. (Argyllshire) [blănnd´-ė] (McAlpine 1832); / bLãũNdɪ/ (AFB˄).
is given in the sense ‘rotten, stale’ by McDonald (2009, 343), who derives it from ON blanda vb ‘to blend, mix’ and its past participle blandinn ‘mixed, mingled, bad’, citing MacBain (1911), Henderson (1910, 214), MacLennan (1925) and Stewart (2004, 408), so also Ó Muirithe (2010, 15); cf. ON blanda vb ‘to mix’ and blandinn ‘mixed, changeable, undependable’ (NO), but Ice. blanda ‘to blend, mix’ and blandinn ‘mixed, mingled, bad (of temper, character, manner)’ (Cleasby 1874). MacBain, however, cites the substantive ON blanda f. ‘whey “blend”’, so also Henderson, referring to a drink of whey and water, while MacLennan and Stewart less specifically cite ON blanda ‘mix, blend’.
SG blanndaidh is translated as ‘rotten, stale, stinking’ (Dwelly 1911; AFB˄) and ‘stale, rotten, addled’ (Stewart), but also occurs as a masculine noun in the sense ‘rotten egg’ (Dwelly; AFB˄).
Dwelly also cites SG blanndair m. and adj., with a cross-reference to blanndaidh, but blanndair in the relevant senses has not been traced and may have been incorrectly cross-referenced by Dwelly.
HSS (1828) gives the senses ‘rotten, stale’, along with examples of usage: ubh blanndaidh (ugh blanndaidh) (North Highlands) ‘a stale egg, an egg half-hatched’ and bainne blanndaidh ‘stale milk, milk soured and thickened’, quoting George Buchanan’s note in Rerum Scoticarum Historia (1582) on the drinking habits of Western Islanders: ‘Serum lactis aliquot annos servatum in conviviis etiam avide bibunt. Id potionis genus blandium appellant’ (‘They sometimes drink whey very greedily in their feasts, after it hath been kept in proper vessels for some years. That kind of drink they call blandium’).
The text and translations given here are from Lib. I, Cap. XXX in Professor Dana Sutton’s 2003/2009 edition˄. HSS’s version reads ‘Serum lactis aliquot annos servatum avide bibunt in conviviis. Id potionis genus Blandium appellant.’
Sutherland (1878, 10) allies Buchanan’s blandium with ‘blaneid’, which is probably a typesetting error for blandie, which may reflect a Scots form (see blandi-, below).
The Rev. Archibald Cook Sutherland (1838–1910) was born in Latheron, Caithness (Ecclegen˄).
SG blanndaidh is probably a truncated form of a Scots compound in initial blandi-, 
A composition form of bland, see below, if it did not occur independently, see blandie, above.
as in blandi-blirek, blandi-kjolek and blandi-swarek, all names of drinks or gruels consisting of bland mixed with meal (Jakobsen 1928, s.v. 2bland, also SND˄, s.v. kaulik); bland (also blaand, blaund) is ‘whey mixed with water’, < ON blanda f. ‘idem’ (Jakobsen; SND˄).
Semantically, the development overall may have been (Scots blandi- sb.) ‘whey with water’ → ‘whey with water soured with age’ → (SG blanndaidh adj.) ‘sour (of milk)’ → ‘addled (of an egg)’. The development of SG blanndaidh as a noun in Gaelic in the sense ‘addled egg’ may be secondary. SND˄ suggests that Scots blaundy ‘an unfertile egg’ is from SG blanndaidh ‘rotten, addled’, while deriving the latter from the Old Norse verb blanda, after MacBain and MacLennan: the suggestion may be correct, but SG blanndaidh seems more likely to be from a Scots word attested in its composition form blandi- and perhaps in Archibald Sutherland’s erroneous form ‘blaneid’ (leg. blandie).