caramelize vs henna

caramelize

verb
  • To undergo this kind of conversion or browning. 

  • To brown (sugar, or a foodstuff containing sugar) by means of heat. 

  • To convert (sugar) into caramel. 

henna

verb
  • To dye or tattoo with henna. 

adj
  • Of a rich reddish-brown colour. 

noun
  • A reddish plant substance, prepared from the dried leaves of this plant, used for temporary tattoos and hair coloring. Hair colorings range from bright red to earth brown to near black. 

  • A shrub, Lawsonia inermis, having fragrant reddish flowers 

  • A rich reddish-brown colour. 

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