fissure vs tranche

fissure

verb
  • To split, forming fissures. 

noun
  • 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. 

  • A state of incompatibility or disagreement. 

tranche

verb
  • To divide into tranches. 

noun
  • A distinct subdivision of a single policyholder's benefits, typically relating to separate premium increments. 

  • One of a set of classes or risk maturities that compose a multiple-class security, such as a CMO or REMIC; a class of bonds. Collateralized mortgage obligations are structured with several tranches of bonds that have various maturities. 

  • A pension scheme's or scheme member's benefits relating to distinct accrual periods with different rules. 

  • A slice, section or portion. 

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