necessitatis
necessitatis is a Latin form of necessitas, meaning “necessity, need; compulsion; distress; close tie, obligation”. It is the genitive singular feminine noun.
Found 68 times in the Latin texts on Socratos.
Where it is used
Cicero, Pro M. Caelio 2: … atino, humanissimo atque optimo adulescenti, meo necessario, ignosco, qui habet excusationem vel pietatis vel necessitatis vel aetatis. si voluit accusare, pietati tribuo, si iussus est, necessitati, si speravit aliquid, pueritiae. …
All forms of necessitas (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.