قسطسقُسْطَاسٌ and قِسْطَاسٌ A balance, or instrument for weighing: (S, Msb, K; and Bd in xvii. 37:) or the most even and most just kind thereof: or such as is just, of whatever kind it be: (K:) or i. q. قَبَّانٌ [a steelyard]: or, as Lth thinks, the iron of the قبّان: or i. q. شَاهِينٌ [the beam of a balance]: (TA:) or i. q. فَرَسْطُونٌ [an arabicized Persian word, signifying a public standard of weights or measures]: (Zj, TA:) also written قصطاس: (K:) said to be Arabic, from القِسْطُ, meaning “ justice: ” (Msb:) or a Greek word arabicized; (IDrd, Msb, K;) and its being so does not impugn the truth of the Kur-án's being  [altogether] Arabic; for when a foreign word is used by the Arabs, and made by them conformable with their language in respect of desinential syntax and determinateness and indeterminateness and the like, it becomes Arabic: (Bd, ubi supra:) pl. قَسَاطِيسُ. (Msb.)