The Collaborative International Dictionary of English v.0.48:

Overcharge \O`ver*charge"\, v. t. [Cf. Supercharge,
   Surcharge.]
   [1913 Webster]
   1. To charge or load too heavily; to burden; to oppress; to
      cloy. --Sir W. Raleigh.
      [1913 Webster]

   2. To fill too full; to crowd.
      [1913 Webster]

            Our language is overcharged with consonants.
                                                  --Addison.
      [1913 Webster]

   3. To charge (a buyer) an excessive price; to charge beyond a
      fair rate or price.
      [1913 Webster]

   4. To exaggerate; as, to overcharge a description.
      [1913 Webster]

   5. (Electricity) To charge (a battery) too much, so as to
      cause damage.
      [PJC]

   Overcharged mine. (Mil.) See Globe of compression, under
      Globe.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overcharge \O`ver*charge"\, v. i.
   To make excessive charges.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overcharge \O"ver*charge`\, n. [Cf. Supercargo,
   Supercharge.]
   [1913 Webster]
   1. An excessive load or burden.
      [1913 Webster]

   2. An excessive charge in an account.
      [1913 Webster]

WordNet (r) 3.0 (2006):

overcharge
    n 1: a price that is too high
    v 1: rip off; ask an unreasonable price [syn: overcharge,
         soak, surcharge, gazump, fleece, plume, pluck,
         rob, hook] [ant: undercharge]
    2: place too much a load on; "don't overload the car" [syn:
       overload, surcharge, overcharge]