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.

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]

radical

/rad·i·cal/ (rad´ĭ-k'l)
1. directed to the root or cause; designed to eliminate all possible extensions of a morbid process.
2. a group of atoms that enters and goes out of chemical combination without change.

free radical  a radical that carries an unpaired electron; such radicals are extremely reactive, with a very short half-life.

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.

radical

[rad′ikəl]
Etymology: L, radix, root
1 n, an atom or group of atoms that contains an unpaired electron. A radical does not exist freely in nature except for O2, NO, and NO2.
2 adj, pertaining to drastic therapy, such as the surgical removal of an organ, limb, or other part of the body.

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]

radical

(of plants) arising from the root or crown.

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]

radical,

n 1. a group of atoms that acts together and forms a component of a compound. The group tends to remain bound together when a chemical reaction removes it from one compound and attaches it to another compound. A radical does not exist freely in nature.
adj 2. a drastic measure to cure or prevent the spread of a serious disease, such as the surgical removal of an organ, limb, or other body part.

radical

1. directed to the cause; going to the root or source 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.

free radical
a radical, extremely reactive, and having a very short half-life (10−5 s or less in an aqueous solution), which carries an unpaired electron.
References in periodicals archive ?
Radical and radical ion reactivity in nucleic acid chemistry.
Free radicals and associated aging were first proposed in 1956 by Dr.
As the compound generates free radicals, it decomposes, Moeller says, so it remains active only for several days.
Dr Taylor's aim is not so much to write a book about the decline of the British aristocracy as to search out the roots of opposition to them, to fill what he identifies as a significant gap in the historical literature, looking at the contribution of anti-aristocratic politics to popular radical activity in the generation after the failure of Chartism in 1848.
One such group was the African Blood Brotherhood for African Liberation and Redemption (ABB), first announced in the pages of West Indian immigrant Cyril Briggs' radical periodical the Crusader.
Low-Energy Electron Interaction with DNA: Bond Dissociation and Formation of Transient Anions, Radicals, and Radical Anions (Lon Sanche).
Naturally, in the Protestant areas north of the River Main and in South Germany as well, the Liberals (whether the left Liberal parties or the National Liberal Party) had successes comparable to and even greater than those of the liberal radicals in Catholic South Germany, and in certain areas they put out a radical platform resembling that of the South German radicals.
One popular theory of aging dictates that with time, free radicals eventually overwhelm this natural defense, leading to various age-related declines.
Also, the mass media, ever quick to declare a victory for radicals, is exaggerating again.
They treated some of the groups with one of three drugs, two that are known to decrease cellular free radicals and a third, an iron chelator, that has been implicated in the generation of free radicals.
To date, there has been no study of the role of free radicals and oxidative damage in the aging larynx.