preoccupied vs ruminating

preoccupied

adj
  • Describing a scientific name that was previously used, a junior homonym. 

  • Concerned with something else; distracted; giving one's attention elsewhere. 

ruminating

noun
  • An act of pondering over, meditation, or reflection. 

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