coherence vs erraticism

coherence

noun
  • The property of having the same wavelength and phase. 

  • A logical arrangement of parts, as in writing. 

  • A semantic relationship between different parts of the same text. 

  • The quality of cohering, or being coherent; internal consistency. 

  • The quality of forming a unified whole. 

erraticism

noun
  • erratic behaviour 

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