Etymology: (1350–1400; ME < LL rādīcālis having roots < L rādīc- (s. of rādīx) root1)
Definition of 'radical'
Princeton's WordNet
1. (noun)group, radical, chemical group (chemistry) two or more atoms bound together as a singleunit and forming part of a molecule
2. (noun)free radical, radical an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygenmolecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule "in the body free radicals are high-energy particles that ricochet wildly and damage cells"
3. (noun)radical a person who has radical ideas or opinions
4. (noun)radical (mathematics) a quantity expressed as the root of another quantity
6. (adj)root, root word, base, stem, theme, radical (linguistics) the form of a word after all affixes are removed "thematic vowels are part of the stem"
7. (adj)extremist, radical, ultra (used of opinions and actions) far beyond the norm "extremist political views"; "radical opinions on education"; "an ultra conservative"
8. (adj)revolutionary, radical markedly new or introducing radicalchange "a revolutionary discovery"; "radical political views"
9. (adj)radical arising from or going to the root or source "a radical flaw in the plan"
10. (adj)radical of or relating to or constituting a linguistic root "a radical verb form"
11. (adj)radical, basal especially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem "basal placentation"; "radical leaves"
1. (adj)radical of or pertaining to the root; proceeding directly from the root
2. (adj)radical hence: Of or pertaining to the root or origin; reaching to the center, to the foundation, to the ultimate sources, to the principles, or the like; original; fundamental; thorough-going; unsparing; extreme; as, radical evils; radical reform; a radicalparty
10. (noun)radical one who advocates radical changes in government or social institutions, especially such changes as are intended to levelclass inequalities; -- opposed to conservative
11. (noun)radical a characteristic, essential, and fundamentalconstituent of any compound; hence, sometimes, an atom
12. (noun)radical specifically, a group of two or more atoms, not completely saturated, which are so linked that their union implies certain properties, and are conveniently regarded as playing the part of a single atom; a residue; -- called also a compoundradical. Cf. Residue