irregular vs raider

irregular

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. 

adj
  • 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) 

  • nonstandard; not conforming to rules or expectations 

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

raider

noun
  • A special forces operative; a commando. 

  • A warship which is light, maneuverable, and fast-moving. 

  • A law enforcement official who conducts a raid on a building in search for illicit goods. 

  • A person who uncovers evidence of improper behavior within governmental or private organizations. 

  • One who engages in a raid; a plunderer. 

  • A person who takes or attempts to take control of a firm against the will of current management by purchasing a controlling interest of stock and acquiring proxies. 

  • A warplane on an air raid. 

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