What is Arura?

Legal Definition
Arura or aroura (Greek: ἄρουρα), is a Homeric Greek word with original meaning "arable land", derived from the verb ἀρόω (aroō), "plough". The word was also used generally for earth, land and father-land and in plural to describe corn-lands and fields. The term arura was also used to describe a measure of land in ancient Egypt (similar in manner to the acre), a square of 100 Egyptian cubits each way. This measures 2700m² or 2/3 of an acre. The oldest attested form of the word is the Mycenaean Greek a-ro-u-ra, written in Linear B syllabic script, originally meant "plough".
-- Wikipedia
Legal Definition
An old English law term, signifying a day's work in plowing.
-- Black's Law Dictionary
Legal Definition
A ploughing.
-- Ballentine's Law Dictionary