circularize vs diffuse

circularize

verb
  • To distribute a circular or circulars to. 

  • To publicize something by publishing and distributing circulars. 

  • To make (something) circular in shape. 

  • To canvass opinion by using a questionnaire. 

diffuse

verb
  • To be spread over or through as in air, water, or other matter, especially by fluid motion or passive means. 

  • To spread over or through as in air, water, or other matter, especially by fluid motion or passive means. 

adj
  • Wordy; verbose. 

  • Everywhere or throughout everything; not focused or concentrated. 

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