infuse vs slip in

infuse

verb
  • To instill as a quality. 

  • To inspire; to inspirit or animate; to fill (with). 

  • To steep in a liquid, so as to extract the soluble constituents (usually medicinal or herbal). 

  • To cause to become an element of something; to insert or fill. 

  • To undergo infusion. 

  • To make an infusion with (an ingredient); to tincture; to saturate. 

slip in

verb
  • To enter discreetly 

  • To include (e.g. a certain word or phrase) into a sentence discreetly 

  • To play a subtle pass into someone in a goalscoring position. 

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