Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Salpīnātes, um, m., a people of Etruria, Liv. 5, 31, 5; 5, 32, 2.
Sing. as adj.: Salpīnas, belonging to the Salpinates: ager, Liv. 5, 32, 4.