rigid vs stern

rigid

adj
  • Uncompromising. 

  • Stiff, rather than flexible. 

  • Fixed, rather than moving. 

  • Rigorous and unbending. 

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. 

stern

adj
  • Grim and forbidding in appearance. 

  • Having a hardness and severity of nature or manner. 

noun
  • A bird, the black tern. 

  • The tail of an animal; now used only of the tail of a dog. 

  • The hinder part of anything. 

  • The post of management or direction. 

  • The rear part or after end of a ship or vessel. 

verb
  • To propel or move backward or stern-first in the water. 

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