Iugerum, iugera or iugus (the last form, as a neuter noun of the third declension, is very common in the oblique cases and in the plural) was a Roman unit of measurement of area, 240 pedes (Roman feet) or 71.0 m in length and 120 pedes or 35.5 m in breadth, containing therefore 28,800 pedes quadratum (Colum. R. R. v.i § 6; Quintil. i.18). That is 0.623 acre or 0.25 ha.
It was the double of the Actus Quadratus, and from this circumstance, according to some writers, it derived its name (Varro, L. L. v.35, Müller, R. R. i.10). [Actus.] It seems probable that, as the word was evidently originally the same as iugum, a yoke, and as actus, in its original use, meant a path wide enough to drive a single beast along, that iugerum originally meant a path wide enough for a yoke of oxen, namely, the double of the actus in width; and that when actus quadratus was used for a square measure of surface, the iugerum, by a natural analogy, became the double of the actus quadratus; and that this new meaning of it superseded its old use as the double of the single actus.
Pliny (Book XVIII. Chapter 3) states "That portion of land used to be known as a "jugerum," which was capable of being ploughed by a single "jugum," or yoke of oxen, in one day; an "actus" being as much as the oxen could plough at a single spell, fairly estimated, without stopping. This last was one hundred and twenty feet in length; and two in length made a jugerum." (The Natural History, Pliny the Elder, translated by John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855).
The uncial division as was applied to the iugerum, its smallest part being the scrupulum of 100 sq ft or 9.2 m². Thus, the iugerum contained 288 scrupula (Varro, R. R. l.c.). The iugerum was the common measure of land among the Romans. Two iugera formed an heredium, a hundred heredia a centuria, and four centuriae a saltus. These divisions were derived from the original assignment of landed property, in which two iugera were given to each citizen as heritable property (Varro, l.c.; Niebuhr, Hist. of Rome, vol. ii pp156, &c., and Appendix ii.).
Columella states (De Re Rustica, Book V) "The square actus is bounded by 120 feet each way: when doubled it forms a iugerum, and it has derived the name iugerum from the fact that it was formed by joining." (Lucius Junius Moderatus Columella. On Agriculture. Translated by Forster and Heffner, Heinemann London MCMLIV).
- This article includes public domain material from A Dictionary of Greek and Roman Antiquities (1842)