In Pandora's box mythology, Hesiod described the container as a jar.
The Greek word used in Works and Days is pithos, a large storage jar commonly used in the ancient Mediterranean. Such jars could hold grain, wine, oil, or other supplies, and some were large enough for storage in a household or underground space. Hesiod's account does not describe a small hinged box.
The expression “Pandora's box” developed much later through translation and artistic tradition. The Renaissance humanist Erasmus translated the Greek vessel using the Latin word pyxis, meaning a box or small container. That choice helped establish the wording familiar in English and many other languages.
This translation difference is one of the most common details people get wrong about the myth. The ancient story centers on a jar, while the modern idiom refers to a box. The jar's opening releases diseases, toil, and other hardships into human life, with hope remaining inside after Pandora closes it.