Words a random library patron didn’t know

I checked out Adrift: Seventy-six days lost at sea by Steven Callahan today and started reading it this evening.   I noticed something very interesting almost right away.  There were lots of penciled in checkboxes next to various lines in the text, and on the lines that were checked, a word or two was underlined in pencil.  In looking at these words, I guessed they were words that one of the previous library patrons who checked out the book didn’t know.   Here’s the list of words:

  • don (as in "don a raincoat")
  • shoal
  • trawlers
  • rogue
  • trends
  • nuances
  • vivid
  • evolved
  • cohesive
  • astrophysicist
  • intuitive extrapolation
  • enthralled
  • exorbitant
  • communion
  • convoluted
  • exhilarating
  • helm
  • crevice
  • quay
  • pandemonium
  • autumn equinox
  • lunatics
  • capstan
  • prone
  • rancorous
  • abated
  • aft

After that, it appears they gave up.  Now, at first I thought maybe it was a child, but I’m not sure that’s the case since there were many fairly complex words that were not underlined (e.g. "perspective", "conclusions", "hydrodynamics").

For some reason, I found this all very interesting.