Source : Webster's Revised Unabridged Dictionary (1913)

Undercharge \Un`der*charge"\, v. t.
   1. To charge below or under; to charge less than is usual or
      suitable fro; as, to undercharge goods or services.

   2. To put too small a charge into; as, to undercharge a gun.

   {Undercharged mine} (Mil.), a mine whose crater is not as
      wide at top as it is deep. --W. P. Craighill.

Undercharge \Un"der*charge`\, n.
   A charge that is less than is usual or suitable.

Source : WordNet®

undercharge
     n 1: a price that is too low
     2: an insufficient charge
     v : charge (someone) too little money [ant: {overcharge}]