What does arpent or arpen mean?
The definition of arpent and arpen
Ar”pent, Ar”pen, n.
Etym: [F. arpent, fr. L. arepennis, arapennis. According to Columella, a Gallic word for a measure equiv. to half a Roman jugerum.]

Formerly, a measure of land in France, varying in different parts of the country. The arpent of Paris was 4,088 sq. yards, or nearly five sixths of an English acre. The woodland arpent was about 1 acre, 1 rood, 1 perch, English.