In Hesiod’s account of Pandora, the vessel was originally called a pithos. A pithos was a large storage jar used in ancient Greece, commonly for grain, oil, or wine.
Hesiod’s Works and Days does not describe Pandora opening a box in the modern sense. The Greek word pithos refers to a substantial jar, and later translations and retellings gradually transformed the object into a “box.”
The familiar phrase “Pandora’s box” became especially influential after the Renaissance. The humanist Erasmus used the Latin expression pyxis, meaning box or small container, when translating or discussing the story. That wording helped establish the version now dominant in English.
This is why “Pandora’s jar” is sometimes used by classicists when discussing the earliest surviving literary account. The myth’s central result remains the release of evils into the world, with hope left inside.