Source : Webster's Revised Unabridged Dictionary (1913)

Rehash \Re*hash"\ (r?*h?sh"), v. t.
   To hash over again; to prepare or use again; as, to rehash
   old arguments.

Rehash \Re*hash"\, n.
   Something hashed over, or made up from old materials.

Source : WordNet®

rehash
     n : old material that is slightly reworked and used again;
         "merely a dull rehash of his first novel"
     v 1: present or use over, with no or few changes
     2: go back over; "retrograde arguments" [syn: {retrograde}, {hash
        over}]