Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Attŭārii, ōrum, m., a German tribe between the Rhine and the Elbe, Vell. 2, 105; Amm. 20, 10 (perh. the Chasuarii of Tacitus, G. 34; cf. Mann. Germ. p. 179, and Rupert. ad Tac. l. c.).