castellum

Borrowed from Latin castellum. Doublet of castell, castle, and château.

castellum (plural castella or castellums)

1. (historical) A small Roman detached fort or fortlet used as a watch tower or signal station.

From castrum (“fort”) +‎ -lum (diminutive suffix).

• (Classical) IPA^(key): /kasˈtel.lum/, [käs̠ˈt̪ɛlːʲʊ̃ˑ]
• (Ecclesiastical) IPA^(key): /kasˈtel.lum/, [käsˈt̪ɛlːum]

castellum n (genitive castellī); second declension

1. castle, fort, citadel, fortress, stronghold
2. (figuratively) a shelter, stronghold, defence, refuge
3. a structure in which the water of an aqueduct is collected, to be distributed by pipes or channels in different directions; a reservoir

Second-declension noun (neuter).

• castilium

• “castellum”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “castellum”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• castellum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• castellum in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette
• “castellum”, in Harry Thurston Peck, editor (1898) Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers
• “castellum”, in William Smith, editor (1854, 1857) A Dictionary of Greek and Roman Geography, volume 1 & 2, London: Walton and Maberly