Tip: also used for money. When using an ATM in Welsh for the first time, I got confused why is said silver only.
Rumour has it this word goes back to PIE and is related to the words for silver used in the romance languages.
And rumour has it right! The Indo-European root arg-" is the source of not only Latin argentum ("silver") and its descendants (e.g. French argent = silver, money) but also Irish airgead (= silver, money), as well as being the reasoning behind the name of that hero of Indian epic, Arjuna ("white, glittery, silver-bright"). Let's not forget, either, the name of the Argentine ("silvery") Republic -- so called because its capital stands on the western bank of the Río de la Plata ("the silver river"). In Welsh, Argentina (the site of Wales's only overseas colony!) is known as Ariannin.
Fantastic comment! For some reason I am very intrigued and interested in hypothesized 'Italo-Celtic' sub branch of the indo-European language family and love seeing examples which offer evidence for this, however I'm aware most of it isn't strictly just vocabulary. Thanks for sharing your knowledge.
Why is silver in the shapes lesson? Triangles, squares, octagons, and chartreuse!