Concave on both sides or surfaces: a biconcave lens. (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.
Use "biconcave" in a sentence
"Real red blood cells owe their astonishing agility to their "biconcave" or tyre-like shape, and to get the same kind of synthetic particles, Samir Mitragotri and his team got their inspiration from the way real red blood cells acquire their final shape in the body."
"Real red blood cells owe their astonishing agility to their "biconcave" or tyre-like shape."
"Again, the more ancient Crocodilia and Lacertilia have vertebrae with the articular facets of their centra flattened or biconcave, while the modern members of the same group have them procoelous."