The crossword solution for the term JUG PLUG is CORK, which is a four letter word. CORK is a natural, impermeable, and buoyant material, the phellem layer of bark tissue that is harvested for commercial use primarily from Quercus suber, which is a species of evergreen oak tree native to southwest Europe and northwest Africa. CORK is used in a variety of products, including bottle stoppers, insulation, and flooring.