Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Caratăcus (Caractăcus and Ca-taratacus, v. Nipp. ad Tac. A. 12, 33), i, m., king of the Silures in Britain, Tac. l. l. sq.; id. H. 3, 45.