Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Madytos (Madytus), i, f., = Μαδυτός, a seaport town in the Thracian Chersonese, now Maitos, Mel. 2, 2, 7; Liv. 31, 16; 33, 38.
Hence, Maduatēni, ōrum, m., the inhabitants of Madytos, Liv. 38, 40.