Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† mammōnas, or mammōna, ae, or mammon, nos, m., = μαμμωνᾶς [properly, Syr. [??]], riches, mammon: non potestis servire Deo et Mammonae, Vulg. Matt. 6, 24; id. Luc. 16, 9; Aug. Serm. Domin. 2, 14: mammona iniquitatis prodere, Aug. Civ. Dei, 1, 10, 3.