In
NetHack and/or
AD&D (and probably other
RPGs as well), a charge is an untapped "use" of a certain class of
magical items. These
items can only be used a certain number of times in their
magical fashion (for example, a
chime of opening), as opposed to
permanent magical items, which can be used
indefinitely (such as a
bag of holding).
Items which rely on charges can usually be
recharged by some complicated process (or a
scroll of charging, depening on the
game).
In NetHack, all wands are charged, as well as several other items (tinning kits, magic markers, etc).