skitter vs tremble

skitter

verb
  • To make a scratching or scuttling noise while, or as if, skittering. 

  • To move hurriedly or as by bouncing or twitching; to scamper, to scurry. 

  • To cause to have diarrhea. 

  • To suffer from a bout of diarrhea; to produce thin excrement. 

  • To move or pass (something) over a surface quickly so that it touches only at intervals; to skip, to skite. 

noun
  • Often skitters: the condition of suffering from diarrhea; thin excrement. 

  • A skittering movement. 

tremble

verb
  • To shake, quiver, or vibrate. 

  • To fear; to be afraid. 

noun
  • A shake, quiver, or vibration. 

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