aperient vs purgative

aperient

noun
  • A laxative, either in the form of a medicine or a food such as asparagus or hops, which has the effect of moving the bowels, or aiding digestion and preventing constipation. 

adj
  • Having a gentle laxative effect. 

purgative

noun
  • something, such as a substance or medicine, that purges; laxative 

adj
  • purging 

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