Source : Webster's Revised Unabridged Dictionary (1913)

Unpack \Un*pack"\, v. t. [1st pref. un- + pack.]
   1. To separate and remove, as things packed; to open and
      remove the contents of; as, to unpack a trunk.

   2. To relieve of a pack or burden. [R.] --Shak.

Source : WordNet®

unpack
     v : remove from its packing; "unpack the presents" [syn: {take
         out}] [ant: {pack}]