In the phrase “Pandora’s box,” the container in Hesiod’s earliest surviving version is a jar. The Greek text of Works and Days uses the word pithos, referring to a large storage vessel rather than a small hinged box.
The modern expression became common because later translators and retellers rendered the vessel as a box. Erasmus helped popularize the Latin phrase pyxis Pandorae, or “Pandora’s box,” in the sixteenth century. That translation strongly influenced later European versions.
A pithos was a substantial ceramic container used in the ancient Mediterranean for storing materials such as grain, oil, or wine. Its size and function make it different from the compact boxes shown in many modern illustrations.
The jar’s contents are commonly called evils or troubles. Hesiod’s account says they escape into the world when Pandora opens it, while hope remains inside. This is separate from the later question of why hope stays behind.