v1.0
Published 01/10/24
aiteal m. [ˈaʰtʲɑɫ̪], gen. aiteil [ˈaʰtʲal], 
(Skye; Glenurquhart) [ɑtʹɑɫ], (Uig, Lewis) [etʹɑɫ] (Faclan bhon t-Sluagh˄), (East Sutherland) /aČal/ (Dorian 1978, 151–52, who notes the by-form (Embo) artal /ɔrTəl/, pp. 46, 52), (Easter Ross) atail, dim. atailean (with a broad dental; pers. comm. Professor Seòsamh Watson).
‘a small amount of something’ is taken by Henderson (1910, 204) to be the same word as Scots atl, attel, although he says ‘it is premature to say on which side the borrowing is.’ Jakobsen (1928) connects atl, attel ‘a small portion of food’ with Nn. etla, atla vb in the sense ‘to deal out food etc.’ (Torp 1992, s.v. 2etla), although ON ætla vb ‘to think, intend etc.’ has a long stressed vowel.
The word aiteal is glossed in dictionaries with a range of senses, but these can be reduced to ‘a small amount of something: a small quantity, a small effect, a portion, a little’; this is extended to ‘a small amount of time, a while, a spell’ and ‘a small view of something, a glimpse’, and to (with regards to the weather, primarily in terms of a reduction) ‘a dry spell between showers, a lull, a calm after a (rain) storm, a respite, a (light) breeze, fair weather, a ray or beam of sun’.
In Easter Ross, the word also has the force of an adverbial prefix, e.g. tha i [a’] cèilidh atail tòrr ‘she’s visiting a bit too much’ (pers. comm. Professor Seòsamh Watson).
MacBain (1896) derives the word from aḋ- + *tel, from a root with the sense ‘weight, money’, hence ‘small amount’, comparing the sense ‘ray’ with Gr. ἀκτίς ‘idem’. The word occurs in Irish as aiteall 
A by-form atal is given by Dinneen (1947) and Ó Dónaill (1977), and referred to by MacLennan (1925, s.v. aiteal).
in the sense ‘stillness, calmness after a storm, cessation from rain, fine spell between showers’, also ‘gladness, joy’ Dinneen (1947), and is connected by de Bhaldraithe (1981, 3) with EG etal ‘ray, (sun)beam; delight, pleasure; fair weather’ (eDIL˄, s.v. 2etal).