Definition of radix in English:
 radix
nounPlural radices ˈradɪksˈreɪks
1Mathematics 
The base of a system of numeration.
 Example sentencesExamples
-  Here r is the base, or radix, and the coefficients d i are the digits of the number.
 -  All that is needed to comprehend the puzzle is understanding that counting by grouping is most easily recorded in the positional notations, radix being the largest group size.
 -  Everything hinges on the assumption that the incremental cost of increasing the radix is the same as the incremental cost of increasing the number of digits.
 
2rare A source or origin of something.
 Judaism is the radix of Christianity
 Example sentencesExamples
-  The unturned chart is called the ‘radical figure’, the radix - the root from which all the symbolism emerges.
 
Origin
  
Early 17th century (in sense 2): from Latin, literally 'root'. sense 1 dates from the late 18th century.