fluttering vs tremble

fluttering

noun

  • Rapid back-and-forth waving or oscillation. 

tremble

noun

  • A shake, quiver, or vibration. 

verb

  • To shake, quiver, or vibrate. 

  • To fear; to be afraid. 

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