'20-dollar' originates from Modern English, formed by combining the numeral '20' (twenty) and the noun 'dollar'. The word 'dollar' itself ultimately comes from Middle High German 'taler' (from 'Joachimsthaler').

'dollar' changed from the German word 'taler' (from 'Joachimsthaler', meaning 'Joachim's valley') into Early Modern English as 'dollar'. The compound form 'twenty-dollar' developed later in English usage to name a unit or a price; the numerical + noun/hyphenated form (e.g. 'twenty-dollar') became common in the 19th–20th centuries, and the numeral form '20-dollar' is a modern typographic variant.

Initially, 'dollar' referred to a silver coin associated with Joachimsthal; over time it became the standard term for the currency unit 'dollar' used in English-speaking countries. '20-dollar' originally denoted a coin or bill worth twenty dollars and now also commonly denotes anything priced at or valued at 20 dollars.