# radical

Pronunciation: US say "RAD-i-kuhl" /ˈɹædɪkəl/; AUS say "RA-di-kuhl" /ˈɹædɪkəl/

## Adjective

1. Having or putting forward extreme views on politics or religion, which may extend to backing violence.
   - Simple: Having very extreme ideas about politics or religion, and sometimes ready to support violence.
   - _Investigators said the attacker had been influenced by radical clerics over several years._
   - _The government banned three radical groups linked to a string of bombings._
2. Affecting the basic nature of something; thorough and far-reaching rather than superficial.
   - Simple: Very great and basic, changing or touching the most important parts of something.
   - _The reforms brought about a radical transformation of the entire curriculum._
   - _What began as minor edits grew into a radical rewrite of the novel._
3. Favoring fundamental change, especially change aimed at the root cause of a matter rather than its surface symptoms.
   - Simple: Wanting big, deep changes that fix the root cause of a problem, not just the surface.
   - _Her views grew more radical in college, as she came to believe the whole system needed rebuilding._
   - _His radical proposal would rebuild the welfare system from the ground up._
4. Boldly original and far from the norm, breaking sharply with what is customary or accepted.
   - Simple: Very new and daring, and very different from what people usually do or accept.
   - _The car's radical styling divided critics when it was unveiled._
   - _His radical approach to teaching math, with no textbooks at all, has drawn national attention._
7. Involving or proceeding by way of free radicals.
   - Simple: Having to do with free radicals, the very reactive particles studied in chemistry.
   - _The polymer is produced by radical polymerization._
   - _Chemists studied the radical mechanism behind the reaction._
13. In mathematics, having to do with a root or radix.
   - Simple: Having to do with the root of a number, or the √ sign used to show it.
   - _The expression is written in radical form rather than as a decimal._
   - _The radical symbol indicates which root to take._
14. Relating to the root of a word, the base form from which other forms derive.
   - Simple: Relating to the root part of a word, the base that other forms grow from.
   - _The radical element of the verb remains unchanged across its conjugations._
   - _Comparative philologists trace the radical components shared by related languages._
16. Of a plant part, arising directly from the root or the base of the stem.
   - Simple: Growing from the root or the base of a plant, close to the ground.
   - _The dandelion's radical leaves form a rosette at ground level._
   - _Botanists described the radical buds emerging from below the soil surface._
18. Of a speech sound, articulated using the root of the tongue, near the pharynx.
   - Simple: In speech, a sound made using the back base of the tongue near the throat.
   - _Phoneticians classify several Arabic consonants as radical sounds._
   - _The radical articulation involves drawing the tongue root toward the pharyngeal wall._

## Noun

5. An atom or molecule with an unpaired electron, which usually makes it highly reactive: a free radical.
   - Simple: A particle with a spare, unpaired electron that is usually very reactive and can damage other molecules.
   - _Because its outer electron is unpaired, the radical reacts readily with almost any molecule it encounters._
   - _Once formed, a hydroxyl radical can damage DNA, proteins, and cell membranes._
6. A person who holds radical opinions, favoring deep or fundamental change rather than gradual reform.
   - Simple: Someone who wants big, deep changes to society or government.
   - _The pamphlet was written by a radical who scorned gradual reform._
   - _Once a moderate, she became a radical after years of frustration._
10. A root of a number or quantity, such as a square root or cube root; also the root sign √, or an expression written with it.
   - Simple: The root of a number, such as a square root, or the √ sign used to write one.
   - _Simplify the radical before adding it to the other terms._
   - _A radical can be rewritten as a number raised to a fractional power._
8. In Chinese and related scripts, the component of a character under which it is classified in dictionaries, usually the part that hints at its meaning.
   - Simple: The part of a Chinese character used to find it in a dictionary, which often hints at its meaning.
   - _The heart radical hints that the character relates to emotion._
   - _Learners memorize each radical to decode unfamiliar characters._
9. A member of a Radical party or faction, such as the reforming wing of the British Liberal Party or the French centrist Radical Party.
   - Simple: A member of a political group called the Radicals, in Britain or France, that wanted reform.
   - _The Liberal government depended on the votes of its Radicals, who kept pushing the party toward bolder reform._
   - _A lifelong Radical, she represented her district in the French National Assembly for nearly twenty years._
15. In Semitic languages, any of the consonants, typically three, that together make up a word's root.
   - Simple: In Semitic languages such as Arabic, one of the consonants, usually three, that form a word's root.
   - _Linguists identify each radical by its position in the consonantal root._
   - _The verb's three radicals recur across all of its derived forms._
17. In number theory, the product of the distinct prime factors of a positive integer.
   - Simple: In math, the number you get by multiplying together the different prime factors of a whole number.
   - _The radical of 360 equals 30, the product of 2, 3, and 5._
   - _Repeated prime factors are counted only once when computing the radical._
19. In Celtic languages, the basic underlying form of an initial consonant, before the Celtic initial consonant mutations alter it.
   - Simple: In Celtic languages, the basic form of a word's first consonant before any sound changes alter it.
   - _Welsh dictionaries list nouns under their radical, not their mutated forms._
   - _The radical resurfaces once the grammatical trigger for mutation is removed._
20. In abstract algebra, any of several related ideals or submodules, such as the radical of an ideal or of a ring or module, built from elements regarded as degenerate.
   - Simple: In advanced math, a special part of a ring, ideal, or module made from certain elements.
   - _The radical of the ideal generated by 4 in the integers is the ideal generated by 2._
   - _Taking the radical twice yields the same ideal as taking it once._

## Adjective

11. Excellent or very impressive; an enthusiastic term of approval. *(dated)*
   - Simple: Very cool, great, or impressive.
   - _The whole road trip turned out to be absolutely radical._
   - _Everyone agreed the new ramp at the park was radical._

## Noun

12. In chemistry, a set of covalently bonded atoms that behaves as one unit in reactions. *(dated)*
   - Simple: A group of atoms that stay joined and act together as one unit in chemical reactions.
   - _In many salts, an acid radical combines with a metal ion._
   - _The ammonium radical behaves as a single charged unit in solution._

## Origin

Radical comes from Middle English radical, from Latin rādīcālis meaning 'of or pertaining to the root,' ultimately tracing back to the Proto-Indo-European root for 'root.'

Source: DictionaryAI, https://dictionaryai.com/define/radical (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).