Hesiod described Pandora’s vessel as a jar.
The Greek word used in the relevant passage is pithos, a large storage jar or earthenware container. Pithoi were commonly used in the ancient Mediterranean for goods such as grain, oil, and wine. The object in Hesiod’s story was therefore not specifically a wooden box.
The familiar expression “Pandora’s box” developed later through translation and artistic tradition. The phrase became especially influential in European languages after Renaissance writers used “box” or a similar small container for the Greek vessel. That wording made the story instantly recognizable, even though it differs from the original description.
The jar is important symbolically because opening it allows diseases, hardships, and other evils to escape. Pandora closes it before the final occupant, Elpis, leaves, although interpretations differ over whether Elpis means hope and whether it remained inside deliberately.