preparatory vs rudimentary

preparatory

adj
  • Of or pertaining to preparation, having the purpose of making something or someone ready, preparative. 

rudimentary

adj
  • Of or relating to one or more rudiments. 

  • Basic; minimal; with less than, or only the minimum, necessary. 

noun
  • One of the rudimentary mammae of boars. 

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