Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Thesprōti, ōrum, m., = Θεσπρωτοί, a people in the south-western part of Epirus, Luc. 3, 179; Liv. 43, 21, 4.
Their land was called Thesprōtĭa, ae, f., = Θεσπρωτία, Plin. 4, 1, 1, § 4; Cic. Att. 6, 3, 2.
Hence,