Lewis & Short

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,

  1. A. Pessĭnuntĭcus, a, um, adj., Pessinuntic; as subst.: Pessĭnun-tĭca, ae, f., Cybele, App. M. 11, p. 259, 7.
  2. B. Pessĭnuntĭus, a, um, adj., Pessinuntian: sacerdos magnae Matris, Cic. Sest. 26, 56: aselli, Gell. 7, 16, 5.