The Greek word for Pandora’s large storage jar is pithos.
A pithos was a large ceramic storage container used in the ancient Greek world, commonly for agricultural goods such as grain or olive oil. Hesiod uses this word for the vessel in the Pandora story. It is therefore more accurate to imagine a substantial earthenware jar than a small hinged box.
The familiar phrase arose through a later Latin translation. Desiderius Erasmus rendered the Greek term as pyxis, a word associated with a box or small container. That choice influenced the European tradition and eventually produced the English expression “Pandora’s box.”
Pyxis is a tempting wrong answer because it is the Latin term connected with the translation shift. Krater and amphora are also Greek vessel names, but they describe different forms and are not the word used for Pandora’s container. Pithos is the precise term tied to Hesiod’s original wording.