Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Dĕcentĭus, ĭi, m., a general of Magnentius, Amm. 15, 6, 4; 16, 12, 5; Eutr. 10, 7.
Dĕcentĭăcus, a, um, adj., pertaining to Decentius.
Subst.: Dĕcen-tiăci, ōrum, m., his adherents, Amm. 18, 9, 3.