clabber vs curdle

clabber

verb
  • To sour or curdle. 

noun
  • Sour or curdled milk. 

  • Wet clay or mud. 

curdle

verb
  • To form curds so that it no longer flows smoothly; to cause to form such curds. (usually said of milk) 

  • To cause a liquid to spoil and form clumps so that it no longer flows smoothly 

  • To clot or coagulate; to cause to congeal, such as through cold. (metaphorically of blood) 

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