(Λάβδακος), a son of the Theban king, Polydorus, the son of Cadmus, by Nycteis, who was descended from a Spartan family. Labdacus lost his father at an early age, and was placed under the guardianship of Nycteus, and afterwards under that of Lycus, a brother of Nycteus. When Labdacus had grown up to manhood, Lycus surrendered the government to him; and on the death of Labdacus, which occurred soon after, Lycus again undertook the guardianship of his son Laius, the father of Oedipus. (Paus. 9.5.2; Eur. Her. 27; Apollod. 3.5.5; comp. NYCTEUS.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890