The Collaborative International Dictionary of English v.0.48:
Radix \Ra"dix\ (r[=a]"d[i^]ks), n.; pl. L. Radices
(r[a^]d"[i^]*s[=e]z), E. Radixes (r[=a]"d[i^]ks*[e^]z). [L.
radix, -icis, root. See Radish.]
1. (Philol.) A primitive word, from which spring other words;
a radical; a root; an etymon.
(a) A number or quantity which is arbitrarily made the
fundamental number of any system; a base. Thus, 10 is
the radix, or base, of the common system of
logarithms, and also of the decimal system of
(b) (Alg.) A finite expression, from which a series is
derived. [R.] --Hutton.
3. (Bot.) The root of a plant.