[ ped-ee-uh n, pee-dee- ]
/ ˈpɛd i ən, ˈpi di- /

noun, plural ped·i·a [ped-ee-uh, pee-dee-uh] /ˈpɛd i ə, ˈpi di ə/. Crystallography.

a crystal form having only a single face, without a symmetrical equivalent: unique to the triclinic system.

Origin of pedion

1885–90; < New Latin < Greek pedíon plain, level ground, diminutive of pédon ground, earth Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019