Dr. Seuss’s publisher once bet him that he couldn’t write a book using only 50 different words.  He decided to prove him wrong, and ended up with Green Eggs and Ham.  The 50 words are:  a,  am,  and,  anywhere,  are, be,  boat,  box,  car,  could,  dark,  do,  eat,  eggs,  fox,  goat, good,  green,  ham,  here,  house,  I,  if,  in,  let,  like,  may,  me,  mouse,  not,  on,  or,  rain,  Sam,  say,  see,  so,  thank, that,  the,  them,  there,  they,  train,  tree,  try,  will,  with,  would,  and you. ()
Chaser the border collie has the largest tested memory of a non-human animal. She knows 1,022 different toys by name and can retrieve them all by name or category. She also understands common nouns (like house and tree) and can infer the meaning of new words based on ones she already knows.  (, , )