undergrown vs unformed

undergrown

adj
  • insufficiently grown; not having grown to a normal or suitable size. 

unformed

adj
  • Not well developed. 

  • Not formed or made. 

  • Not having a definite form; shapeless; amorphous. 

  • Not grouped into any constellation. 

  • Decomposed, or resolved into parts; having the form destroyed. 

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