di·a·ton·ic 
(dī′ə-tŏnĭk)
(dī′ə-tŏnĭk)adj.
Music
Music
Of or using only the seven tones of a standard scale without chromatic alterations.
[Late Latin diatonicus, from Greek diatonikos : dia-, dia- + tonos, tone; see TONE.]
di′a·toni·cal·ly adv.
di′a·toni·cism (-ĭ-sĭz′əm) n.