ab- vs sub-

ab-

prefix

  • Away from; outside of. 

  • A unit of electromagnetic charge in the centimeter-gram-second system: the abcoulomb. 

  • From. 

sub-

prefix

  • under, beneath 

  • subsidiary, secondary 

  • almost, nearly 

How often have the words ab- and sub- occurred in a corpus of books? (source: Google Ngram Viewer )