Decumanus
A decumanus (plural: decumani) was an east-west street in a Roman camp or settlement. The name derives from the Latin term for tenth, which was apparently a reference to the via decumana, the division between the ninth and tenth cohort in a legionary encampment. The main east-west street in a Roman settlement was called the decumanus maximus. In an orthogonally planned settlement, the decumanus maximus would typically run between the east and west gate (or barring walls, the primary east and west entrance into the settlement), and would typically intersect with the main north-south street, the cardo maximus, at or near the forum of the settlement.
