rivulet vs topping

rivulet

noun
  • Perizoma affinitatum, a geometrid moth. 

  • A small brook or stream; a streamlet; a gill. 

topping

noun
  • The tail of an artificial fly. 

  • Either of the cables that support the ends of a spar or boom. 

  • Any food item added on top of another, such as sprinkles on ice cream or pepperoni on pizza. 

  • The act of cutting off the top of something. 

  • The act of raising one extremity of a spar higher than the other. 

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