Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Marcŏmăni and -manni, ōrum, m. [marka, a march, border; the marchmen, borderers], a Germanic people, a portion of the tribe of the Suevi, who, after their defeat by Drusus, removed from the Rhine and the Main to the country of the Boii (Bohemians), Caes. B. G. 1, 51; Tac. G. 42; id. A. 2, 46; 62; Vell. 2, 108; 109; 110 and 382; Stat. S. 3, 3, 170; Vop. Aur. 13, 3.
Hence,