apt vs fit for purpose

apt

adj
  • Suitable; appropriate; fit or fitted; suited. 

  • Ready; especially fitted or qualified (to do something); quick to learn. 

  • Having a habitual tendency; habitually liable or likely; disposed towards. 

noun
  • An apartment; a flat. 

fit for purpose

adj
  • appropriate, and of a necessary standard, for its intended use. 

How often have the words apt and fit for purpose occurred in a corpus of books? (source: Google Ngram Viewer )