underdeveloped vs unfeathered

underdeveloped

adj
  • immature and not fully developed 

  • having a low level of economic productivity and technological sophistication 

  • of a film that has had insufficient development before being fixed 

unfeathered

adj
  • Lacking feathers 

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