Also found in: Encyclopedia.
Having or formed by three planes meeting at a point.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Mathematics) having or formed by three plane faces meeting at a point
(Mathematics) a figure formed by the intersection of three lines in different planes
[C18: from tri- + Greek hedra base, seat + -al1]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
1. having, or formed by, three planes meeting in a point: a trihedral angle.n.
2. the figure determined by three planes meeting in a point.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.