radical

(noun) (chemistry) two or more atoms bound together as a single unit and forming part of a molecule. Synonyms: group, chemical group.

(noun) 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. Synonyms: free radical. Examples: "In the body free radicals are high-energy particles that ricochet wildly and damage cells."

(noun) a person who has radical ideas or opinions.

(noun) (mathematics) a quantity expressed as the root of another quantity.

(noun) a character conveying the lexical meaning of a logogram.

(noun) (linguistics) the form of a word after all affixes are removed. Synonyms: root, root word, base, stem, theme. Examples: "Thematic vowels are part of the stem."

(adj) (used of opinions and actions) far beyond the norm. Synonyms: extremist, ultra. Examples: "Extremist political views." "Radical opinions on education." "An ultra conservative."

(adj) markedly new or introducing radical change. Synonyms: revolutionary. Examples: "A revolutionary discovery." "Radical political views."

(adj) arising from or going to the root or source. Examples: "A radical flaw in the plan."

(adj) of or relating to or constituting a linguistic root. Examples: "A radical verb form."

(adj) 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. Synonyms: radical (vs. cauline), basal. Examples: "Basal placentation." "Radical leaves."