ŏb-ăro, āvi, ātum, 1,
v. n., to plough around, plough up : cum hostes obarāssent quicquid herbidi terreni extra murum erat, Liv. 23, 19, 14.
ob-arō āvī, —, āre, to plough around, plough up: quicquid herbidi terreni erat, L. ...
An Elementary Latin Dictionary