Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
gentĭcus, a, um, adj. [gens], of or belonging to a nation, national (post-Aug.): quibus more gentico continuum ferri tegimen, Tac. A. 3, 43; 6, 33: pro gentica devotione, Tert. de Anim. 39.