Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Aulis, is or ĭdis, f., = Αὐλίς, a seaport town in Bœotia, from which the Grecian fleet set sail for Troy, Verg. A. 4, 426: Aulin (acc.), Luc. 5, 236.