▪ Jeffery1938: »There was practical agreement among the early authorities that the word means primarily ‘a balance’, and then metaphorically ‘justice’ (cf. Rāġib, Mufradāt, 413; LA, viii, 59). It was also very generally recognized as a loan-word. Some considered it as a genuine Ar word, a variant of ↗qisṭ,1
but the weight of the authorities as we see from al-Suyūṭī, Itq, 323; Muzhir, i, 130; al-Ǧawālīqī, Muʕarrab, 114; al-Ṯaʕālibī, Fiqh, 318, and al-Siǧistānī, 257, was in favour of its being taken as a borrowing from Grk.2
Its foreign nature is indeed indicated by the variety of spellings we find.3 It was evidently an early borrowing, for it occurs in verses of ʕAdī b. Zayd, al-Nābigha,4
and others. The origin of the word, however, is not easy to settle. Sachau in his notes to the Muʕarrab, p. 51, quotes Fleischer as suggesting that it goes back to the Lat constans as used of the libra.5
Fraenkel, Fremdw, 282, suggests a hypothetical [Grk] *koústōs as a possible origin, and in WZKM, vi, 261, would interpret it from zugostasía. Vullers, Lex, ii, 725, thought that it was probably a mangling of the Grk zeûgos ‘yoke’, and Dvořák, Fremdw, 77 ff., would derive it from xéstēs from the Lat sextarius used as a measure of fluid and dry materials. All these suggestions seem to be under the influence of the theory of the philologers that the word is of Grk origin. It would seem much more hopeful to start from the Aram qsṭʔ, qysṭʔ, qwsṭʔ meaning ‘measure’, or the Syr qsṭā. The final s here [in Ar], however, presents a difficulty, and Vollers, ZDMG, 1, 633,6
suggests that it is from the Grk dikastḗs ‘judge’, which in Syr is dīqasṭōs (BB, in PSm, 891), and with the d- taken as the genitive particle, would give us qasṭōs. This, influenced by the similar dqasṭā also = dikastḗs, would give us qisṭās. This is very ingenious and may be true, but Mingana, Syr Influence, 89, thinks it simpler to take it from [Syr] qsṭā representing xéstēs in some form in which the final -s had survived.«