Definitions from Wiktionary ( )

▸ adjective:  Favoring fundamental change, or change at the root cause of a matter.
▸ adjective:  (botany, not comparable) Pertaining to a root (of a plant).
▸ adjective:  Pertaining to the basic or intrinsic nature of something.
▸ adjective:  Thoroughgoing; far-reaching.
▸ adjective:  (lexicography, not comparable) Of or pertaining to the root of a word.
▸ adjective:  (phonology, phonetics, not comparable, of a sound) Produced using the root of the tongue.
▸ adjective:  (chemistry, not comparable) Involving free radicals.
▸ adjective:  (mathematics) Relating to a radix or mathematical root.
▸ adjective:  (slang, 1980s & 1990s) Excellent; awesome.
▸ noun:  (historical, 19th-century Britain, politics) A member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).
▸ noun:  (historical, early 20th-century France) A member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.
▸ noun:  A person with radical opinions.
▸ noun:  (arithmetic) A root (of a number or quantity).
▸ noun:  (linguistics) In logographic writing systems such as the Chinese writing system, the portion of a character (if any) that provides an indication of its meaning, as opposed to phonetic.
▸ noun:  (linguistics) In Celtic languages, refers to the basic, underlying form of an initial consonant which can be further mutated under the Celtic initial consonant mutations.
▸ noun:  (linguistics) In Semitic languages, any one of the set of consonants (typically three) that make up a root.
▸ noun:  (chemistry) A group of atoms, joined by covalent bonds, that take part in reactions as a single unit.
▸ noun:  (organic chemistry) A free radical.
▸ noun:  (algebra, commutative algebra, ring theory, of an ideal) Given an ideal I in a commutative ring R, another ideal, denoted Rad(I) or √, such that an element x ∈ R is in Rad(I) if, for some positive integer n, xⁿ ∈ I; equivalently, the intersection of all prime ideals containing I.
▸ noun:  (algebra, ring theory, of a ring) Given a ring R, an ideal containing elements of R that share a property considered, in some sense, "not good".
▸ noun:  (algebra, ring theory, of a module) The intersection of maximal submodules of a given module.
▸ noun:  (number theory) The product of the distinct prime factors of a given positive integer.

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