bullwhip vs knout

bullwhip

verb
  • To beat with a bullwhip. 

noun
  • A whip made from plaited leather, often with a knotted end, for use with livestock. 

knout

verb
  • To flog or beat with a knout. 

noun
  • A leather scourge (multi-tail whip), in the severe version known as 'great knout' with metal weights on each tongue, notoriously used in imperial Russia. 

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