Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Sēgō̆brīga, ae, f., = Σηγόβριγα, the chief town of the Celtiberians (in Hispania Tarraconensis), near the modern Priego, Plin. 36, 22, 45, § 160.
Hence, Sēgobrī-genses, ium, m., the inhabitants of Segobriga, Plin. 3, 3, 4, § 25; Front. 3, 10, 6.