Pithos is the Greek word for the large storage jar in the earliest Pandora myth.
Hesiod’s Works and Days, composed in the eighth century BCE, does not describe Pandora opening a small hinged box. It uses the word pithos, a term for a substantial earthenware jar used to store commodities such as grain, oil, or wine. These jars could be large enough to stand on the floor or be partly buried.
The familiar phrase “Pandora’s box” developed later through translation and artistic tradition. The Latin writer Erasmus used the expression pyxis, meaning a box or container, in the sixteenth century. That wording helped establish the form now dominant in English.
An amphora is another ancient Greek vessel, but it usually has two handles and a narrower body than a storage pithos. A krater was used for mixing wine and water, while a lekythos was a smaller vessel associated especially with oil. Those distinctions make pithos the specific answer here.