equable vs erratic

equable

adj
  • Not easily disturbed; tranquil. 

  • Unvarying, calm and steady; constant and uniform. 

  • Free from extremes of heat or cold. 

erratic

adj
  • Unsteady, random; prone to unexpected changes; not consistent. 

  • Deviating from normal opinions or actions; eccentric; odd. 

noun
  • A rock moved from one location to another, usually by a glacier. 

  • Anything that has erratic characteristics. 

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