Medical Definition of radical
: free radical; also : a group of atoms bonded together that is considered an entity in various kinds of reactions
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Dictionary: Definition of "radical" Thesaurus: All synonyms and antonyms for "radical" Spanish Central: Translation of "radical" Nglish: Translation of "radical" for Spanish speakers Britannica English: Translation of "radical" for Arabic speakers Britannica.com: Encyclopedia article about "radical"
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