Old English seolfor, Mercian sylfur "silver; money," from Proto-Germanic *silubra- (cf. Old Saxon silvbar, Old Frisian selover, Old Norse silfr, Middle Dutch silver, Dutch zilver, Old High German silabar, German silber "silver; money," Gothic silubr "silver"), from a common Germanic/Balto-Slavic term (cf. Old Church Slavonic s(u)rebo, Russian serebro, Polish srebro, Lithuanian sidabras "silver") of uncertain relationship and origin. According to Klein's sources, possibly from a language of Asia Minor, perhaps from Akkadian sarpu "silver," literally "refined silver," related to sarapu "to refine, smelt."
As an adjective from late Old English (cf. silvern). As a color name from late 15c. Of voices, words, etc., from 1520s in reference to the metal's pleasing resonance; silver-tongued is from 1590s. The silver age (1560s) was a phrase used by Greek and Roman poets. Chemical abbreviation Ag is from Latin argentum "silver," from the usual PIE word for the metal (see argent), which is missing in Germanic.