portion vs tranche

portion

verb
  • To divide into amounts, as for allocation to specific purposes. 

  • To endow with a portion or inheritance. 

noun
  • An allocated amount. 

  • That which is divided off or separated, as a part from a whole; a separated part of anything. 

  • One's fate; lot. 

  • A wife's fortune; a dowry. 

  • The part of an estate given or falling to a child or heir; an inheritance. 

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