In the Latin language of the ancient Roman Empire, castra (singular castrum) were buildings or plots of land reserved for or constructed for use as a military defensive position. The word appears in both Oscan and Umbrian (dialects of Italic) as well as in Latin. In classical Latin the word castra means "great legionary encampment" and included "marching", "temporary" and "fortified permanent" ones, while the diminutive form castellum was used for the smaller forts, which were usually, but not always, occupied by the auxiliary units and used as logistic bases for the legions, as explained by Vegetius. A generic term is praesidium ("guard post or garrison"). The terms stratopedon ("army camp") and phrourion ("fort") were used by Greek language authors, in order to designate the Roman castra and the Roman castellum respectively. In English, the terms "Roman fortress", "Roman fort" and "Roman camp" are commonly used for the castra. However, scholastic convention tends toward the use of the word "camp", "marching camp" and "fortress" as a translation of castra, and the use of the word "fort" as a translation of castellum. These conventions are usually followed and found in scholarly works.