stifle vs strengthen

stifle

verb
  • To keep in, hold back, or repress (something). 

  • To prevent (a breath, cough, or cry, or the voice, etc.) from being released from the throat. 

  • To make (something) unable to be heard by blocking it with some medium. 

  • To prevent (something) from being revealed; to conceal, to hide, to suppress. 

  • To cause (someone) difficulty in breathing, or a choking or gagging feeling. 

  • To feel smothered; to find it difficult to breathe. 

  • To cause (a dog, horse, or other four-legged mammal) to dislocate or sprain its stifle joint. 

  • To die of suffocation. 

  • To make (an animal or person) unconscious or cause (an animal or person) death by preventing breathing; to smother, to suffocate. 

  • To treat (a silkworm cocoon) with steam as part of the process of silk production. 

noun
  • An act or state of being stifled. 

  • A bone disease of this region. 

  • The joint between the femur and tibia in the hind leg of various four-legged mammals, especially horses, corresponding to the knee in humans. 

strengthen

verb
  • To reinforce, to add to, to support (someone or something) 

  • To make strong or stronger; to add strength to; to increase the strength of; to fortify. 

  • To empower; to give moral strength to; to encourage; to enhearten. 

  • To grow strong or stronger. 

  • To substantiate; to corroborate (a belief, argument, etc.) 

  • To augment; to improve; to intensify. 

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