Lewis & Short

Phthīa, ae, f., = Φθία, a city in Thessaliotis, the birthplace of Achilles, Mel. 2, 3, 4; Verg. A. 1, 284.
Hence,

  1. A. Phthīas, ădis, f., a Phthian woman, Ov. H. 7, 165 (al. Phthia).
  2. B. Phthīōta, ae, and Phthī-ōtes, ae, m., = Φθιώτης, a Phthiote, Cic. Tusc. 1, 10, 21.
    In plur., the Phthiotes, Plin. 4, 7, 14, § 28; Liv. 33, 32; 34; 36, 15.
  3. C. Phthīōtis, ĭdis, f., = Φθιῶτις, Phthiotis, a district of Thessaly, in which Phthia lay, Plin. 4, 8, 15, § 29; Liv. 28, 6.
  4. D. Phthī-ōtĭcus, a, um, adj., = Φθιωτικός, of Phthiotis, Phthiotian, poet. for Thessalian: ager, Liv. 33, 3: Tempe, Cat. 64, 35.
  5. E. Phthīus, a, um, adj., of or belonging to Phthia: vir, i. e. Achilles, Prop. 2, 13, 38 (2, 5, 22); cf. Achilles, Hor. C. 4, 6, 4: rex, i. e. Peleus, Ov. Am. 2, 17, 17.