the ephah: the everyday dry measure for grain and flour in ancient Israel, holding roughly twenty liters (a little over half a bushel)
The ephah was the ordinary measuring unit a household or a trader used for grain and flour: not a weight but a fixed volume, the amount a standard container held. Its size was set by relation to the other units. It was a tenth of the largest measure (the homer, a full donkey load), ten times the small daily ration called the omer, and equal in capacity to the liquid measure known as the bath, so the same volume served for dry goods and for wine or oil.
Because buying and selling depended on it, the law returns again and again to the honest ephah. Merchants are forbidden to keep a large one for buying and a small one for selling, and the prophets denounce those who shrink the ephah to cheat the poor. When the standard is trusted, trade is fair; when it is tampered with, the whole economy turns to robbery.
In one vision the word names the measuring vessel itself rather than the amount it holds. The prophet sees a physical ephah, a basket large enough for a woman to sit inside, carried off through the air as a picture of the nation's guilt being removed from the land.