stain vs tranche

stain

verb
  • To discolour. 

  • To cause to seem inferior or soiled by comparison. 

  • To coat a surface with a stain 

  • To treat (a microscopic specimen) with a dye, especially one that dyes specific features 

  • To taint or tarnish someone's character or reputation 

  • To become stained; to take a stain. 

noun
  • A reagent or dye used to stain microscope specimens so as to make some structures visible. 

  • A discoloured spot or area. 

  • Any of a number of non-standard tinctures used in modern heraldry. 

  • A blemish on one's character or reputation. 

  • A substance used to soak into a surface and colour it. 

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 stain and tranche occurred in a corpus of books? (source: Google Ngram Viewer )