fissure vs nonregularity

fissure

noun
  • A state of incompatibility or disagreement. 

  • A long, narrow crack or opening made by breaking or splitting, especially in rock or earth. 

  • A groove, deep furrow, elongated cleft or tear between body parts or in the substance of an organ; a sulcus. 

  • A break or slit in tissue usually at the junction of skin and mucous membrane. 

verb
  • To split, forming fissures. 

nonregularity

noun
  • The state or condition of being nonregular. 

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