flax vs knock out

flax

noun
  • A plant of the genus Linum, especially Linum usitatissimum, which has a single, slender stalk, about a foot and a half high, with blue flowers. Also known as linseed, especially when referring to the seeds. 

  • The flax bush, a plant of the genus Phormium, native to New Zealand, with strap-like leaves up to 3 metres long that grow in clumps. 

  • The fibers of Linum usitatissimum, grown to make linen and related textiles. 

knock out

verb
  • To fall asleep, especially suddenly. 

  • To lose the scent of hounds in fox-hunting. 

  • To eliminate from a contest or similar. 

  • To put to sleep. 

  • To complete, especially in haste; knock off. 

  • To render unconscious, as by a blow to the head. 

  • To strike or bump (someone or something) out. 

  • To exhaust. 

  • To cause a mechanism to become non-functional by damaging or destroying it. 

  • To communicate (a message) by knocking. 

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