of age vs underdeveloped

of age

prep
  • Old enough to be considered an adult (in law, or by society generally). 

  • Having existed for a certain period of time; used in referring to a person's age. 

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 

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