uncia

Building upon Varro, most modern Latinists derive this word from ūnicus (“unique”) + -ia, itself from ūnus (“one”) (from Proto-Indo-European *óynos) in the sense of twelfths making up the base unit of various ancient systems of measurement. Following Heron of Alexandria, Weiss instead postulates a borrowing from Ancient Greek ὀγκία (onkía, “uncia”), from ὄγκος (ónkos, “weight”); he considers the loss of medial /i/ necessitated by the traditional etymology unproblematic but the derivation from "unique" semantically implausible.