In Hesiod’s Works and Days, the vessel later known in English as Pandora’s Box was a pithos.
A pithos was a large ancient Greek storage jar, commonly used for commodities such as grain, oil, or wine. Hesiod’s Greek text uses this word for the container Pandora opens. The vessel’s scale and storage function differ from the small wooden or jeweled box shown in many modern illustrations.
The familiar English expression developed through later translation history and became firmly established in European culture. That change is why modern audiences often picture a box even though the earliest surviving literary account describes a jar.
Other Greek vessel terms are not interchangeable. An amphora is a two-handled storage or transport jar, a krater is a mixing vessel, and a kylix is a drinking cup. Pithos is the specific term connected with Hesiod’s Pandora passage.