bat, in a measurement system, ancient Hebrew unit of liquid and dry capacity. Estimated at 37 litres (about 6.5 gallons) and approximately equivalent to the Greek metrētēs, the bat contained 10 omers, 1 omer being the quantity (based on tradition) of manna allotted to each Israelite for every day of the 40-year sojourn in the desert recorded in the Bible.