snicker vs titter

snicker

noun
  • A stifled or broken laugh. 

  • A player who snicks the ball. 

verb
  • To emit a snicker, a stifled or broken laugh. 

  • To whinny. 

  • To utter through a laugh of this kind. 

titter

noun
  • A nervous or somewhat repressed giggle. 

  • A woman's breast. 

verb
  • To laugh or giggle in a somewhat subdued or restrained way, as from nervousness or poorly-suppressed amusement. 

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