undercharge \un`dercharge"\, v. t.
   1. to charge below or under; to charge less than is usual or
      suitable for; as, to undercharge goods or services.
      1913 webster

   2. to put too small a charge into; as, to undercharge a gun.
      1913 webster

   undercharged mine mil., a mine whose crater is not as
      wide at top as it is deep. --w. p. craighill.
      1913 webster
see also:
undercharged mine