radical

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radical

 [rad´ĭ-kal]
1. thorough or sweeping; directed to the cause or root of a morbid process.
2. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.
color radical chromophore.
free radical a radical that carries an unpaired electron; such radicals are extremely reactive, with a very short half-life.
oxygen radical a toxic metabolite of oxygen, such as superoxide or singlet oxygen, capable of damaging microorganisms and normal tissues.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

rad·i·cal

(rad'i-kăl), Do not confuse this word with radicle.
1. In chemistry, a group of elements or atoms usually passing intact from one compound to another, but usually incapable of prolonged existence in a free state (for example, methyl, CH3); in chemical formulas, a radical is often distinguished by being enclosed in parentheses or brackets.
2. Thorough or extensive; relating or directed to the extirpation of the root or cause of a morbid process; for example, a radical operation.
3. Denoting treatment by extreme, drastic, or innovative, as opposed to conservative, measures.
4. Synonym(s): free radical
5. A functional group in a molecule or molecular entity.
[L. radix (radic-), root]
Farlex Partner Medical Dictionary © Farlex 2012

radical

(răd′ĭ-kəl)
adj.
1. Departing markedly from the usual or customary; extreme or drastic: a radical change in diet.
2. Medicine Relating to or being surgery that is extreme or drastic in an effort to eradicate all existing or potential disease: radical hysterectomy.
3. Botany
a. Of, relating to, or arising from a root: radical hairs.
b. Arising from the base of a stem or from a below-ground stem or rhizome: radical leaves.

rad′i·cal·ly adv.
rad′i·cal·ness n.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

rad·i·cal

(rad'i-kăl)
1. chemistry A group of elements or atoms usually passing intact from one compound to another, but usually incapable of prolonged existence in a free state (e.g., methyl, CH3); in chemical formulas, a radical is often distinguished by being enclosed in parentheses or brackets.
2. Directed to the extirpation of the root or cause of a morbid process, e.g., a radical operation.
3. Denoting treatment by extreme, drastic, or innovative, as opposed to conservative, measures.
4. Synonym(s): free radical.
[L. radix (radic-), root]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

radical

(of plants) arising from the root or crown.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

rad·i·cal

(rad'i-kăl)
1. In chemistry, a group of elements or atoms usually passing intact from one compound to another, but usually incapable of prolonged existence in a free state (e.g., methyl, CH3).
2. Thorough or extensive; relating or directed to the extirpation of the root or cause of a morbid process.
3. Denoting treatment by extreme, drastic, or innovative, as opposed to conservative, measures.
[L. radix (radic-), root]
Medical Dictionary for the Dental Professions © Farlex 2012