Lewis & Short

Baetis (Bĕtis, Paul. Nol. Carm. ad Aus. 10, 236), is, m. (acc. Baetin, Plin. 3, 1, 3, § 12 (al. Baetim); Mart. 9, 62, 2; Claud. Fesc. 12, 31; Mall. Theod. 285; Claud. Laud. Stil. 2, 238:

  1. I. BAETEM, Inscr. Grut. 153, 4; abl. Baete, Liv. 28, 22, 1: Baeti (al. Baete), Plin. 3, 1, 3, § 13; Amm. 23, 6, 21), = Βαῖτις, a river in Southern Spain, called by the inhabitants Certis, now Guadalquivir, Liv. 28, 16, 2; Mel. 3, 1, 5; Plin. 3, 1, 3, §§ 7 and 13.
  2. II. Deriv.: Baetĭcus, a, um, adj., on or belonging to the Bœtis: provincia, Tac. H. 1, 53: regiones, Col. 1, pr. 20: vocabulum, id. 5, 1, 5: oves, id. 7, 2, 4: lana, Mart. 12, 65, 4; Juv. 12, 40.
    1. B. Subst.: Baetĭca, ae, f., = Βαιτική, the province of Bœtica, lying on the Bœtis, in Southern Spain, distinguished for its excellent wool, now Andalusia and a part of Granada, Mel. 2, 6, 3; 2, 4, 7; 3, 1, 6; 3, 6, 1; Plin. 3, 1, 3, § 7; 11, 37, 76, § 196; Tac. H. 1, 78 al.
      Hence,
      1. 2. Adj.: Baetica lana, Plin. 8, 48, 73, § 191: lacernae, made of the Bœtican wool, Mart. 14, 133.
        Baetĭci, ōrum, m., the inhabitants of Bœtica, Plin. Ep. 1, 7.