1. (used of opinions and actions) far beyond the norm
   "radical opinions on education";
   - extremist, ultra
    
2. Markedly new or introducing fundamental change
   "radical political views";
   - revolutionary
    
3. Arising from or going to the root or source
   "a radical flaw in the plan"
    
4. (linguistics) of or relating to or constituting a linguistic root
   "a radical verb form"
    
5. (botany) 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
   "radical leaves";
   - basal
    
6. [N. Amer, slang] Of the highest quality, skill, etc.; very good or impressive
   "a radical reporter";
   - ace [informal], A-one [informal], crack [informal], first-rate, super, tiptop, topnotch [informal], top-notch [informal], tops [informal], A1 [informal], top-class, gnarly [N. Amer, informal], excellent, first-class, fantabulous [informal], splendid, ripping [Brit, archaic, informal], mean [informal], outstanding, lush [Brit, informal], brilliant, beezer [UK, archaic], stellar [informal], awesome [informal], top-drawer, dope [N. Amer, informal], socko [N. Amer, informal], righteous [US, slang], fab [Brit, informal], crucial [slang], rad [N. Amer, slang], nang [Brit, slang], phat [slang], legit [US, slang], awesomesauce [informal], amazeballs [informal], beaut [Austral, NZ, informal], lit [US, slang], storming [Brit, informal], blinding [Brit, slang], stonking [Brit, informal], brill [Brit, informal], wicked [slang], cushty [Brit, informal], def [slang], magic [Brit, slang], smokin' [slang], smoking [slang], sick [N. Amer, slang]

1. A person who has radical ideas or opinions
   "The radical proposed a complete overhaul of the existing system";
   - rad [informal]
    
2. (chemistry) two or more atoms bound together as a single unit and forming part of a molecule
   "The hydroxyl radical is an important chemical group in many organic compounds";
   - group, chemical group
    
3. 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";
   - free radical
    
4. (mathematics) a quantity expressed as the root of another quantity
   "The equation contained a square root radical"
    
5. A character conveying the lexical meaning of a logogram
   "In Chinese characters, the radical often gives a clue to the meaning of the whole character"
    
6. (linguistics) the form of a word after all affixes are removed
   "thematic vowels are part of the radical";
   - root, root word, base, stem, theme

Sounds like: racks, wadical, r

Derived forms: radicals

See also: basic, immoderate, new, super-duper [informal], superior

Type of: actor, amount, atom, building block, character, descriptor, doer, form, graph, grapheme, graphic symbol, measure, quantity, signifier, unit, word form, worker

Part of: ideogram, ideograph, molecule

Encyclopedia: Radical, Republican, Democratic and Progressive