Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Gonni, ōrum, m., a town of Thessaly near the Vale of Tempe, now Lycóstomo, Liv. 33, 10; 36, 10.
Also in the sing.: Gonnus, i, m., Liv. 42, 54; 67; 44, 6.