lepton vs old penny

lepton

noun
  • A coin used since ancient times in Greece, serving in modern times as one hundredth of a phoenix, a drachma, and a euro (as the Greek form of the Eurocent). 

  • An elementary particle that has a spin of 1/2 (i.e., is a fermion) and does not interact via the strong nuclear force; examples include the electron, the muon, the neutrino and the tauon. 

  • A small, bronze Judean coin from the 1st century BCE, considered by some to be the widow's mite. 

old penny

noun
  • A coin worth one old penny. 

  • The pre-decimalisation United Kingdom penny, ¹⁄₂₄₀ of a pound sterling. Symbol: d 

  • The pre-decimalisation Irish penny, ¹⁄₂₄₀ of an Irish pound. Symbol: d 

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