fathead vs loon

fathead

noun
  • An idiot; a fool. 

  • A blobfish, Psychrolutes microporos 

  • Any of several species of fish of the genus Cubiceps 

  • A labroid food fish of California; the California sheephead. Semicossyphus pulcher. 

  • A cyprinid fish of the Mississippi valley, Pimephales promelas, the black-headed minnow. 

loon

noun
  • A crazy or deranged person; a lunatic. 

  • A boy, a lad. 

  • Any of various birds, of the order Gaviiformes, of North America and Europe that dive for fish and have a short tail, webbed feet and a yodeling cry. 

  • An English soldier of an expeditionary army in Ireland. 

  • A simpleton. 

  • A harlot; mistress. 

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