Australia’s decimal currency almost ended up being named the Royal (the Prime Minister Robert Menzies wanted it to be so), though ultimately they went with the dollar, out of cold-war-era affinity with the US.
Dollar, a shortening of Joachimstaler... Someone explain how the fuck something which I suppose is pronounced "yo-ah-keen-staah-laerh" eventually became dollar instead of "stalle" or "talle"
Short version: for some reason Thal means valley (Neanderthal means "Neander Valley" where the fossils were first found.)
A German valley known for silver became shorthand slang for money, so a Thal became synonymous with money (like buck, clam, bead, dough, green, etc.).
Thal, through time and clumsy mouths, became dal (doll).
So the slang for money became dal and that grew into daller, and the Angles did what they do to spelling and teeth and did their own thing. So now we have dollar as Germanic slang for money.
Then a new land is settled and it has a ton of immigrants who all muddle their languages but somehow learn slang super easy, like we all learn new languages, so we are left with dollar meaning money when it originally was a silver mine in a valley from around Charlemagne.
The region the currency was minted was called "Joachimsthal", so the name became "Joachimsthaler", with the suffix -er signifying it is something from there. The English suffix -er works similarly - a Londoner is a person from London.
By the way, nowadays the word is spelled "Tal", not "Thal". I'll use that spelling from now on to also avoid any confusion with the thorn sound im English - "Th" in German is pronounced the same as "T".
Because "Joachimstaler" has a lot of syllables, eventually people just said "Taler" instead, there was only one currency from a place with "-tal" at the end anyways. All German regions have dialects whose prononciation of certain letters differs from standard German - which standardized spelling conventions. As such, people from some other regions wouldn't have written "Tal" but rather "Dal", had they named the region. Small interjection: Bordeaux instead of Porto: A woman with a Saxon dialect accidentally booked the wrong ticket on the phone.
As such the Dutch / Low Germans named the currency "Daler" which then became "Dollar".
You should read about Brazil and our history of hyperinflation. The “old coin” OP is referring was Réis. Then it came the Cruzeiro (comes from cross and a constellation we see in our sky). Then the hyperinflation came and we had too many zeros in our day-to-day currency. So we cut 3 zeros and the currency became Cruzado (crossed). But it didn’t work, so we cut again and it became Cruzeiro Novo and then again Cruzado.
Finally, a team managed to control the inflation by making the economy flow with the dollar. We indexed the prices and salaries to an index called OTN and then BTN and finally this BTN became the Real.
