arcis
arcis is a Latin form of arx, meaning “citadel, fortress; height, summit”. It is the genitive singular feminine adjective.
Found 64 times in the Latin texts on Socratos.
Where it is used
Caesar, De Bello Civili 3.66: … rus, relicto interiore vallo maiorem adiecerat munitionem. Ita minora castra inclusa maioribus castelli atque arcis locum obtinebant. Item ab angulo castrorum sinistro munitionem ad flumen perduxerat circiter passus CCCC, quo …
Plautus, Casina 3.5.664: ita ómnes sub árcis, sub léctis laténtes
All forms of arx (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.