Old English gold, from Proto-Germanic *gulth- (cf. Old Saxon, Old Frisian, Old High German gold, German Gold, Middle Dutch gout, Dutch goud, Old Norse gull, Danish guld, Gothic gulþ), from PIE root *ghel- "yellow, green," possibly ultimately "bright" (cf. Old Church Slavonic zlato, Russian zoloto, Sanskrit hiranyam, Old Persian daraniya-, Avestan zaranya- "gold;" see Chloe).
As an adjective from c.1200. In reference to the color of the metal, it is recorded from c.1400. Gold rush is attested from 1859, originally in an Australian context. Gold medal as first prize in a contest is from 1908.