evergreen vs permanent

evergreen

adj
  • Of a document, a piece of software, or a dataset, being continually up-to-date (as opposed to being published at regular intervals and outdated in the meantime) 

  • Being a clause which causes an automatic renewal of a contract unless action is taken. 

  • Of plants, especially trees, that do not shed their leaves seasonally. 

  • Suitable for transmission at any time; not urgent or time-dependent. 

verb
  • To extend the term of a patent beyond the normal legal limit, usually through repeated small modifications. 

  • To set the repayment rate of a loan at or below the interest rate, so low that the principal will never be repaid. 

noun
  • A shrub or tree that does not shed its leaves or needles seasonally. 

  • A conifer tree. 

  • A news story that can be published or broadcast at any time. 

permanent

adj
  • Lasting for an indefinitely long time. 

  • Without end, eternal. 

noun
  • A card whose effects persist beyond the turn on which it is played. 

  • A chemical hair treatment imparting or removing curliness, whose effects typically last for a period of weeks; a perm. 

  • Given an n⨯n matrix a_ij,, the sum over all permutations 𝜋, of ∏ᵢ₌₁ⁿa_i𝜋(i). 

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