A historical German coin worth exactly one-eighth of a thaler, commonly minted in the 17th-18th centuries.
Compound of 'achtel' (eighth) and 'thaler' (large silver coin). The thaler itself came from Joachimsthal in Bohemia, and this smaller denomination created a practical subdivision for everyday commerce.
The achtelthaler is why we say 'thaler' became 'dollar'—when German immigrants came to America, they brought familiar coin names, and Dutch traders already called them 'daalder,' which English speakers simplified to 'dollar.'
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