black tea vs infusion

black tea

noun
  • Tea leaves which have been "fermented" (actually, oxidized) before drying to enhance their flavour (cf. green tea). 

  • A cup of tea served without milk. 

infusion

noun
  • A product consisting of a liquid which has had other ingredients steeped in it to extract useful qualities. 

  • The administration of liquid substances directly into a vein for medical purposes; perfusion. 

  • The act of steeping or soaking a substance in liquid so as to extract medicinal or herbal qualities. 

  • The act of installing a quality into a person. 

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