leaven vs outgrowth

leaven

noun
  • Anything that induces change, especially a corrupting or vitiating change. 

  • Any agent used to make dough rise or to have a similar effect on baked goods. 

verb
  • To add a leavening agent. 

  • To cause to rise by fermentation. 

  • To temper an action or decision. 

  • To imbue; to infect; to vitiate. 

  • To rise or become larger. 

outgrowth

noun
  • A byproduct or consequence of an action or event. 

  • An appendage of an animal. 

  • A branch or offshoot of a plant. 

  • Excessive growth. 

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