Pertaining or relating to a root or to roots.Specifically— In botany, belonging to the root: opposed to cauline. See radical leaves and radical peduncle, below.In philology, of the nature of or pertaining to a root, or a primary or underived word or main part of a word: as, a radical word; a radical letter or syllable; radical accentuation.In mathematics, consisting of or indicating one of the roots of a number: as, a radical expression; the radical sign.In chem., noting any atom or group of atoms which is, for the moment, regarded as a chief constituent of the molecules of a given compound, and which does not lose its integrity in the ordinary chemical reactions to which the substance is liable.Making part of the essential nature of the subject or thing concerned; existing inherently; intrinsic; organic: as, radical defects of character; a radical fault of construction; the radical principles of an art or of religion.Of or pertaining to the root or foundation of the subject; concerned with or based upon fundamental principles; hence, thoroughgoing; extreme: as, a radical truth; a radical difference of opinion; radical views or measures; the Radical party in British politics.Of or pertaining to a political party or body of persons known as Radicals (see II., 4, below): as, a Radical candidate; the Radical program.Synonyms There may be a distinction between a radical reform, change, cure, or the like, and one that is thorough, entire, complete, or thoroughgoing, radical emphasizing only the fact of going to the root, whether there is thoroughness or entireness or not. Yet that which is radical is likely to be thorough, etc.n. In philology:n. A radical word or part of a word; especially, a primitive word or verbal element serving as a root of inflected or derivative words.n. A radical letter; a letter forming an essential part of the primitive form or root of a word. Also radicle.n. In chem., an element or group of combined elements which remains after one or more elements have been removed from a compound. (See the quotation.)n. In music, same as root.n. A person who holds or acts according to radical principles; one who pursues a theory to its furthest apparent limit; an extremist, especially in politics.n. In algebra, a quantity expressed as a root of another quantity.n. See the adjectives.In astrology, belonging to the radix or original scheme of nativity; in horary astrology, ripe and proper for judgment.n. A minute vessel which unites with others to form a large branch or trunk. See radicle, 2.n. In England, the name given to a white hat which was formerly somewhat worn by Radicals, owing to the fact that Henry Hunt [a radical English politician, 1773–1835] wore a white hat at various political gatherings in 1820.
