layer vs tranche

layer

verb
  • To cut or divide into layers. 

  • To arrange in layers. 

noun
  • One of the items in a hierarchy. 

  • A person who lays anything, such as tiles or a wager. 

  • A (usually) horizontal deposit; a stratum. 

  • A shoot of a plant, laid underground for growth. 

  • An item of clothing worn under or over another. 

  • A single thickness of some material covering a surface. 

  • A mature female bird, insect, etc. that is able to lay eggs. 

  • A hen kept to lay eggs. 

  • one in a stack of (initially transparent) drawing surfaces that comprise an image; used to keep elements of an image separate so that they can be modified independently from one another. 

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