from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Having as many planes as required for complete symmetry in a given crystal system.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Having as many plane faces as needed for the highest degree of symmetry in its system
from the GNU version of the Collaborative International Dictionary of English
- adj. Having all the planes required by complete symmetry, -- in opposition to
from The Century Dictionary and Cyclopedia
- In mineralogy, having all the similar edges or angles similarly replaced, as a crystal.
From holo- + Ancient Greek ἕδρα (hedra, "seat"). (Wiktionary)