rid vs unlade

rid

verb
  • To free (something) from a hindrance or annoyance. 

adj
  • Released from an obligation, problem, etc. (usually followed by of). 

unlade

verb
  • To disburden; take the burden from; relieve. 

  • To discharge a cargo; discharge a burden. 

  • To discharge the cargo from. 

  • To unload. 

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