irregular vs rustic

irregular

adj
  • rough 

  • without symmetry, regularity, or uniformity 

  • not regular; having sides that are not equal or angles that are not equal 

  • whose faces are not all regular polygons (or are not equally inclined to each other) 

  • nonstandard; not conforming to rules or expectations 

  • not following the regular or expected patterns of inflection in a given language 

noun
  • A soldier who is not a member of an official military force and who may not use regular army tactics. 

  • One who does not regularly attend a venue. 

rustic

adj
  • Crude, rough. 

  • Country-styled or pastoral; rural. 

  • Simple; artless; unaffected. 

  • Unfinished or roughly finished. 

noun
  • A noctuoid moth. 

  • Any of various nymphalid butterflies having brown and orange wings, especially Cupha erymanthis. 

  • A (sometimes unsophisticated) person from a rural area. 

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