In the oldest Greek account, Pandora opened a jar. Hesiod’s Works and Days uses the Greek word pithos, a large storage jar, rather than describing a small box.
The familiar English expression “Pandora’s box” developed later through translation history. The Renaissance humanist Erasmus translated pithos into the Latin pyxis, meaning a box or small container, helping establish the wording that became standard in European languages. The popular phrase therefore differs from the container named in Hesiod’s surviving Greek text.
A pithos was a practical vessel used in the ancient Greek world for storing commodities such as grain, oil, or wine. Artistic and literary retellings have often turned it into a decorative box, which is why the modern image differs from the early text. “Jar” is the specific answer for the original container, while “Pandora’s box” remains the established idiom.