Diazeuctic \Di`a*zeuc"tic\, Diazeutic \Di`a*zeu"tic\, a. [Gr. ? disjunctive, fr. ? to disjoin; dia` through, asunder + ? to join, yoke.] (Anc. Mus.) Disjoining two fourths; as, the diazeutic tone, which, like that from F to G in modern music, lay between two fourths, and, being joined to either, made a fifth. [Obs.]