rocking vs swaying

rocking

noun
  • The motion of something that rocks. 

  • The abrading of a copper plate with a rocker, preparatory to mezzotinting. 

  • The motion by which the design on a steel mill is transferred to a copper cylinder. 

adj
  • Excellent; great. 

  • Shaking, swaying or moving back and forth. 

swaying

noun
  • The motion of something that sways. 

  • An injury caused to a horse's back by violent strains or overloading. 

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