What is the meaning of Azumbre?

An ancient measure of volume of liquids used in Castile, equivalent to 2.016 litres.

azumbre, a unit of liquid measure equivalent to about 2 L a liquid measure, an eighth of a [Term?] or about 2 L

an ancient measure of volume of liquids used in Castile, equivalent to 2.016 litres

Source: wiktionary.org