adamantine vs rigid

adamantine

adj
  • Made of adamant, or having the qualities of adamant; incapable of being broken, dissolved, or penetrated. 

  • Like the diamond in hardness or luster. 

noun
  • Synonym of adamantium 

rigid

adj
  • Rigorous and unbending. 

  • Stiff, rather than flexible. 

  • Fixed, rather than moving. 

  • Uncompromising. 

noun
  • An airship whose shape is maintained solely by an internal and/or external rigid structural framework, without using internal gas pressure to stiffen the vehicle (the lifting gas is at atmospheric pressure); typically also equipped with multiple redundant gasbags, unlike other types of airship. 

  • A bicycle with no suspension system. 

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