Perhaps from the same as mueo (through the idea of tuition); a tale, i.e. Fiction ("myth") -- fable.
see GREEK mueo
1. a speech, word, saying.
2. a narrative, story;
a. a true narrative.
b. a fiction, a fable; universally, an invention, falsehood: 2 Peter 1:16; the fictions of the Jewish theosophists and Gnostics, especially concerning the emanations and orders of the aeons, are called μυθοι (A. V. fables) in 1 Timothy 1:4; 1 Timothy 4:7; 2 Timothy 4:4; Titus 1:14. (Cf. Trench, § xc., and references under the word γεναλογια.)