Epoxy is a very strong type of glue. Epoxy is used in the construction of airplanes and cars, among other things.
While epoxy can be used for a variety of substances made of a certain chemical compound, from paints to plastics, it most commonly means an industrial-strength adhesive. Epoxy is so sticky and so strong that it can hold together the parts of a boat or a bicycle, and keep the fin of a surfboard attached, even in the water. The word epoxy combines epi-, "in addition" and oxy, from oxygen.