irregular vs solitary

irregular

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

  • without symmetry, regularity, or uniformity 

  • rough 

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

  • 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. 

solitary

adj
  • Not associated with others of the same kind. 

  • Performed, passed, or endured alone 

  • Living or being by oneself; alone; having no companion present 

  • Not much visited or frequented; remote from society 

  • Single; individual; sole. 

  • gloomy; dismal, because of not being inhabited. 

  • Not inhabited or occupied; without signs of inhabitants or occupation; desolate; deserted 

noun
  • One who lives alone, or in solitude; an anchorite, hermit or recluse. 

  • Solitary confinement. 

  • The state of being solitary; solitude 

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