immature vs unformed

immature

adj
  • Not fully formed or developed; not grown. 

  • Childish in behavior; juvenile. 

noun
  • An immature member of a species. 

unformed

adj
  • Not formed or made. 

  • Not well developed. 

  • 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 immature and unformed occurred in a corpus of books? (source: Google Ngram Viewer )