inconsistent vs irregular

inconsistent

adj
  • Lacking internal consistency; self-contradicting; not compatible with itself. 

  • Not consistent or coherent in thought or behavior. 

  • Having the property that a contradiction can be derived. 

  • Not compatible (with another thing); incompatible, discrepant, at odds. 

irregular

adj
  • nonstandard; not conforming to rules or expectations 

  • without symmetry, regularity, or uniformity 

  • rough 

  • 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) 

  • 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. 

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