tentative vs unperfected

tentative

adj
  • Of or pertaining to a trial or trials; essaying; experimental. 

  • restrained; polite; feeling one's way, not using full force. 

  • Uncertain; subject to future change. 

noun
  • A trial; an experiment; an attempt. 

unperfected

adj
  • Not perfected. 

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