An Etymological Dictionary of Astronomy and Astrophysics

A prefix meaning thick.

Etymology (EN): From Fr. pachy-, from L., from Gk. pachys “thick,” akin to Av. bazah “high, deep,” Baloci baz “thick, dense,” ON bingar “heap,” Latvian biezs “dense, thick.”

Etymology (PE): Bazâ-, from Av. bazah, Baloci baz, as above; cf. Waxi bâj “thickness,” variant dabz, → concentrated.