Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Pīsae, ārum, f., a very ancient eity of Etruria, a colony of Pisa in Elis, still called Pisa: Alpheae ab origine Pisae, urbs Etrusca solo, Verg. A. 10, 179 Serv.; Just. 20, 1, 11; Luc. 2, 401; Liv. 21, 39.
Hence,
Pīsānus, a, um, v. Pisae, A.