1916, in reference to certain chemical compounds, from epi- + first element of oxygen. Epoxy- is used as a prefix in chemistry to indicate an oxygen atom that is linked to two carbon atoms of a chain, thus forming a "bridge" ("intramolecular connection" is one of the chemical uses of epi-). Resins from epoxides are used as powerful glues. Hence the verb meaning "to bond with epoxy" (1965). Related: Epoxied.