posterity vs spawn

posterity

noun
  • All the future generations, especially the descendants of a specific person. 

spawn

noun
  • Any germ or seed, even a figurative source; offspring. 

  • The numerous eggs of an aquatic organism. 

  • Mushroom mycelium prepared for (aided) propagation. 

  • The buds or branches produced from underground stems. 

  • The location in a game where characters or objects spontaneously appear. 

verb
  • To produce or deposit (eggs) in water. 

  • To bring forth in general. 

  • (To cause) to appear spontaneously in a game at a certain point and time. 

  • To reproduce, especially in large numbers. 

  • To induce (aquatic organisms) to spawn. 

  • To generate, bring into being, especially non-mammalian beings in very large numbers. 

  • To plant with fungal spawn. 

  • To deposit (numerous) eggs in water. 

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