Guinea Xích Đạo (Vietnamese) comes from Vietnamese Đạo, from Chinese 刀, from English Dollar, from Dutch dollar, from English dollar, from Dutch daler, from German taler, from German Joachimsthaler — heel of the foot; heel.
Ancestry of “Guinea Xích Đạo”, step by step
Guinea Xích Đạo traces back through 3 separate lines of ancestry.
A gold coin originally worth twenty shillings; later (from 1717 until the adoption of decimal currency) standardised at a value of twenty-one shillings