Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Pessĭnūs and Pesĭnūs, untis, f. (acc. masc. Pessinuntem, Cic. Har. Resp. 13, 28), = Πεσσινοῦς and Πεσινοῦς, a very ancient town in Galatia, on the borders of Phrygia Major, celebrated for its worship of Cybele; the modern Bala Hissar, Cic. Fam. 2, 12, 2: si mater Idaea a Pessinunte Romam advecta foret, Liv. 29, 10 (in Plin. 5, 32, 42, § 146, the true read. is Pisinuus).
Hence,