Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
bĕātĭtas, ātis, f. [beatus], the condition of the beatus, happiness, a blessed condition, blessedness, = beata vita, felicitas; a word first used by Cic.: aut ista sive beatitas, sive beatitudo dicenda sunt (utrumque omnino durum, sed usu mollienda nobis verba sunt), Cic. N. D. 1, 34, 95 (but he seems to have used neither of the two words again): apud Ciceronem beatitas et beatitudo, Quint. 8, 3, 32; so Macr. Somn. Scip. 1, 9; App. Doct. Plat. 2.
Plur., Aug. Civ. Dei, 21, 17.