Strong’s Greek
G3355 — metretes
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
μετρητής
metretes — pronounced met-ray-tace'
from 3354; a measurer, i.e. (specially), a certain standard measure of capacity for liquids:--firkin. see GREEK for 3354
1 occurrence in the KJV.
John 2:6
And there were set there six waterpots of stone, after the manner of the purifying of the Jews, containing two or three firkins apiece.