unlade vs unpack

unlade

verb
  • To unload. 

  • To discharge a cargo; discharge a burden. 

  • To disburden; take the burden from; relieve. 

  • To discharge the cargo from. 

unpack

verb
  • To unzip, decompress. 

  • To empty containers that had been packed. 

  • To undergo separation of its features into distinct segments. 

  • To remove from a package or container, particularly with respect to items that had previously been arranged closely and securely in a pack. 

  • To analyze a concept or a text; to explain. 

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