ONlwSG

seall sb. [ʃɑuɫ̪] is derived by Mackay (1897, 90) from ON hel ‘Hel, the goddess of the realm of the dead; the realm of the dead; death’ (NO), specifically in the Sutherland phrase cuiridh mi seall ort ‘I will do for you’. However, ON hel, assuming initial h- > SG s- via back-formation, would formally yield SG *seal *[ʃɑɫ̪]. McDonald (2009, 361–62) rejects a loan from hel on the basis that seall is probably the Scottish Gaelic verb ‘to look, see’, although a verbal stem here is syntactically implausible.

The Scottish Gaelic verb goes back to EG sellaiḋ ‘sees, perceives’, itself a derivative of EG sell ‘eye; glance’ (eDIL^˄), a reflex of which appears to survive in the phrase SG Dia seall oirnn ‘God save us’, probably a contraction of gun toireadh Dia seall oirnn ‘may God bestow a look upon us’.

So Dwelly 1911, s.v. seall; contrast vocative followed by imperative use in a Dhia, seall oirnn ‘God, help us/have pity on us’ (cf. Armstrong 1825, s.v. Dia and seall).

The compounds seall-dùisg ‘conscious view, 

Cf. seall-fhios ‘ocular proof, certainty’ (Armstrong 1825), consisting of an initial-element-stressed closed compound.

as opposed to seall-aislinge’ 

Consisting of second-element-stressed open compounds, with the final adjectival elements in the genitive.

(Faclan bhon t-Sluagh^˄, s.v. seall-duisg) may contain the same reflex. The sentiment invoked in Dia seall oirnn is also expressed in the phrase gun sealladh E/Dia/Sealbh (Mòr)/sealbh oirnn 

With the conjunction gun^m + mixed (i.e. imperative/conditional) tense constituting the optative mood (Cox 2017, 272).

‘may He/God/(Great) Providence/luck look upon us’, 

The elliptical gun sealladh oirnn is also found.

the Wester Ross version of which would be gun sealladh seoll oirnn (cf. Wentworth 2003, s.v. goodness), where seoll is a dialectal form of seall (Robertson 1907b, 93). The apparent reduplication in the use of both sealladh and seoll here may be the result of conflation of Dia seall oirnn, or similar, and gun sealladh (sealbh) oirnn. Mackay’s cuiridh mi seall ort may also contain this reflex, but here in an unfavourable sense parallel to cuiridh mi an droch-shùil ort ‘I’ll put the evil-eye on you, I’ll do you harm’. Cf. the use of the verbal phrase seall air in the sense ‘to affect someone or something adversely’: (Wester Ross) dh’fhaodadh bhon bha e air medication gun do sheoll an deoch na bu mhios’ air ‘perhaps as he was on medication the drink affected him worse’ (Wentworth, s.v. affect).

However, Domhnall Uilleam Stiùbhart (pers. comm.) suggests that Mackay’s seall may be for SG seul(a) [ˈs̪eːɫ̪(ə)] ‘mark’ (< Eng. seal), and that his cuiridh mi seall ort might be the equivalent of (Lewis) cuiridh mi seula ort/cuiridh mi mo sheula ort in the sense ‘I’ll give you a black eye’. This may be the case: Mackay’s article certainly contains spelling and typesetting errors (for example, s.v. duil fhear). (Mackay’s Sutherland pronunciation of SG seall would probably have been seoll (cf. Robertson 1907b, 88, 93); his Sutherland pronunciation of seul(a) may well have been [ˈs̪iːl(ə)], cf. the Sutherland poet Rob Donn’s aicill rhyme seuladh : sgrìobhaidh (Mackay 1829, 39: ... feuchaidh mi a’ bhann | Tha agam air a seuladh, | O làimh sgriobhaidh [sic] Ruairidh Mhann [‘I’ll produce the sealed contract I have from Ruairidh Mann’s hand’]).)