Lewis & Short

Lynceus (dissyl.), ĕi (gen. Lyncei, dissyl., Hor. S. 1, 2, 90 Orell. ad loc.; voc. Lynceu, Prop. 3, 32, 9), m., = Λυγκεύς, a Messenian, and one of the Argonauts, brother of Idas, and son of Aphareus, famed for the sharpness of his sight: non possis oculo quantum contendere Lynceus, Hor. Ep. 1, 1, 28: Lyncei oculi, id. S. 1, 2, 90; cf. Val. Fl. 1, 462; Hyg. Fab. 14; Val. Max. 1, 8, n. 14; Plin. 2, 17, 15, § 78; Ov. F. 5, 711; Prop. 2, 34 (3, 32), 9.
Hence,

  1. I. Lyncēus, a, um, adj., = Λύγκειος, of Lynceus, Lyncean, Ov. F. 5, 709.
        1. b. Transf., sharp-sighted: quis est tam Lynceus, qui in tantis tenebris nihil offendat, Cic. Fam. 9, 2, 2.
      1. 2. Lyncī-des, ae, m., a descendant of Lynceus, Ov. M. 5, 99; 4, 767.
  2. II. A son of Ægyptus, and husband of Hypermnestra, who alone was saved by his wife when all his brothers were put to death, Ov. H 14, 123; Hyg. Fab. 273.
  3. III. Son of Thestius, and brother of Althæa, who was slain by Meleager, Hyg. Fab. 173; 174.
  4. IV. One of the companions of Æneas; acc. Lyncĕă, Verg. A. 9, 768.