τετράχορδος

A. four-stringed, ὄργανον Ath. 4.183a; λύρα Str. 13.2.4.

II. Subst. ‐χορδον,τό, tetrachord, i.e. scale of four notes, comprising two tones and a half, Arist. Pr. 922b8, Fr. 47, Plu. 2.1021e, etc.: metaph., (sc. παθῶν) Aristo Stoic. 1.85, cf. Jul. Caes. 315c.