1529, from M.E.
gaud "deception, trick," also "ornamental bead, rosary" (c.1300), possibly from Anglo-Fr.
gaudir "be merry, scoff," from L.
gaudere "rejoice." Alternate (less likely) etymology is from M.E.
gaudy-green "yellowish-green," originally "green dye" obtained from a plant formerly known as
weld, from a Gmc. source (see
weld (n.)), which became
gaude in O.Fr. The Eng. term supposedly shifted sense from "weld-dye" to "bright."