epode vs nursery rhyme

epode

noun
  • A kind of lyric poem, invented by Archilochus, in which a longer verse is followed by a shorter one. 

  • The after song; the part of a lyric ode which follows the strophe and antistrophe. 

nursery rhyme

noun
  • A short poem or song for children, mostly anonymous or handed down by folklore 

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