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correspondence in size, form, and arrangement of parts on opposite sides of a plane, or around an axis. adj., adj symmet´rical.
bilateral symmetry the configuration of an irregularly shaped body (such as the human body or that of higher animals) that can be divided by a longitudinal plane into halves that are mirror images of each other.
radial symmetry that in which the body parts are arranged regularly around a central axis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Symmetrical arrangement, as of an organism or a body part, along a central axis, so that the body is divided into equivalent right and left halves by only one plane.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
bilateral symmetryadjective Referring to a form divisible into equal mirror halves in one plane only—e.g., the right half of an organism mirrors the left.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
bilateral symmetryadjective Referring to a form divisible into equal mirror halves in one plane only
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
bilateral symmetryan animal body structure in which there is a head and a rear with the body organs arranged so that a section through the midline from dorsal (upper) to ventral (lower) surfaces would divide the organism into almost identical right and left halves. Most higher invertebrates (e.g. PLATYHELMINTHS, ANNELIDS, ARTHROPODS) and all vertebrates are bilaterally symmetrical. Compare RADIAL SYMMETRY.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005