Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Suessetāni, ōrum, m., a people of Hispania Tarraconensis, Liv. 25, 34; 34, 20; 39, 42.
Hence, adj.: Suessetānus, a, um: ager, Liv. 28, 24.