Definition of "coplanar" [co•plan•ar]

• Lying or occurring in the same plane. Used of points, lines, or figures. (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.

• "If the image is not coplanar with the crosshairs (that is the image is either in front of or behind the crosshairs), then putting your eye at different points behind the ocular causes the crosshairs to appear to be at different points on the target."
• "Do not let your foot enter the three-dimensional space dedicated to the next stall, which is bounded above and below by an invisible wall coplanar with the partition."
• "Levels of PBDEs, PCDDs, PCDFs, and coplanar PCBs in edible fish from California coastal waters."