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" ;

3. (

• radical ,

) a person who has radical ideas or opinions ;

4. (

• radical

) (mathematics) a quantity expressed as the root of another quantity ;

5. (

• radical ,

) 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" ;

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" ;

3. (

• radical

) arising from or going to the root or source; "a radical flaw in the plan" ;

4. (

• radical ,

) 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; "basal placentation"; "radical leaves" ;