"radical" in the noun sense
1. group, radical, chemical group
chemistry) two or more atoms bound together as a single unit and forming part of a molecule
2. free radical, radical
an atom or group of atoms with at least one unpaired electron in the body it is usually an oxygen molecule 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"
a person who has radical ideas or opinions
mathematics) a quantity expressed as the root of another quantity
a character conveying the lexical meaning of a logogram
6. 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"
"radical" in the adjective sense
1. extremist, radical, ultra
used of opinions and actions) far beyond the norm
"extremist political views"
"radical opinions on education"
"an ultra conservative"
2. revolutionary, radical
markedly new or introducing radical change
"a revolutionary discovery"
"radical political views"
arising from or going to the root or source
"a radical flaw in the plan"
of or relating to or constituting a linguistic root
"a radical verb form"
5. 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
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
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