Definition of "octahedral" [oc•ta•he•dral]

• Having eight plane surfaces. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Rutile is made up mostly of titanium dioxide with two rarer polymorphs anatase or octahedrite, which is a tetragonal mineral of pseudo-octahedral habit, and brookite, which is an orthorhombic mineral, the Doctor explained to her."
• "I think aragonite, olivine and ice have hexagonal crystals whereas diamond has octahedral."
• "Ever. I slip my hands through the holes and into gloves, and pick up the biggest rock I see, a perfect 5-carat octahedral crystal three times older than the human species, formed during the age of the mastodons."