carceris
carceris is a Latin form of carcer, meaning “prison; starting gate (of a racecourse)”. It is the genitive singular masculine noun.
Found 38 times in the Latin texts on Socratos.
Where it is used
Cicero, In C. Verrem 2.5.118: patres hi quos videtis iacebant in limine, matresque miserae pernoctabant ad ostium carceris ab extremo conspectu liberum exclusae; quae nihil aliud orabant nisi ut filiorum suorum postremum spiritum or …
Ovid, Metamorphoses 4.453: Carceris ante fores clausas adamante sedebant
All forms of carcer (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.