Castra

In the Roman Republic and the Roman Empire, the Latin word castrum,[1] plural castra, was a military-related term.

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In Latin usage, the singular form castrum meant 'fort', while the plural form castra meant 'camp'.[2] The singular and plural forms could refer in Latin to either a building or plot of land, used as a fortified military base.[3]

In English usage, castrum commonly translates to "Roman fort", "Roman camp" and "Roman fortress". However, scholastic convention tends to translate castrum as "fort", "camp", "marching camp" or "fortress".[3]

Romans used the term castrum for different sizes of camps – including large legionary fortresses, smaller forts for cohorts or for auxiliary forces, temporary encampments, and "marching" forts. The diminutive form castellum was used for fortlets,[4] typically occupied by a detachment of a cohort or a centuria.

For a list of known castra, see List of castra.