superhuman vs unimaginable

superhuman

adj
  • Beyond what is possible for a human being. 

noun
  • A human being with remarkable abilities or superpowers. 

unimaginable

adj
  • unable to be imagined; inconceivable or mind-boggling; beyond belief 

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