Lewis & Short

Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.

Thūcȳdĭdes, is, m., = Θουκυδίδης, a celebrated Greek historian, Cic. Or. 9, 30 sq.; 65, 219; id. Brut. 83, 287 sq.; id. de Or. 2, 13, 56; Quint. 10, 1, 73.
Hence, Thūcȳdĭdīus, a, um, adj., of or belonging to Thucydides, Thucydidian: genus (orationis), Cic. Opt. Gen. 6, 16.
Subst. plur.: Thūcȳdĭdĭi, ŏrum, m., imitators of Thucydides, Cic. Or. 9, 30.