μετρητής metrētḗs

Meaning

a measurer, i.e. (specially), a certain standard measure of capacity for liquids

In the King James Version: firkin

Derivation: from G3354 (μετρέω);

Where it is used

• John 2:6 Now six stone water jars had been set there for the Jewish rites of purification. Each could hold from twenty to thirty gallons.