Definition of plug:
(n) :
a pronged
connecting device which fits
into a mating
socket; any piece of wood, metal, or other substance used to stop or
fill a
hole; a stopple
"I pushed the plug back into the electrical socket and the lamp began to glow again."
(v) :
to
stop with a plug; to make tight by stopping a hole; to
mention a particular product or service
"he attempted to plug the leaks with some caulk."