rivulet vs winterbourne

rivulet

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

  • Perizoma affinitatum, a geometrid moth. 

winterbourne

noun
  • A stream that only flows in winter or after wet weather, particularly in an area rich in limestone. 

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