From The New Harvard Dictionary of Music. (1986) Ed. D.M. Randel. Cambridge, MA: Bellknap Press of Harvard University Press.

"[from Greek cheir, hand]. The use of movement of the hand to indicate approximate pitch or melodic contour to singers. The practice is evidently of great antiquity and is widely distributed (e.g., in ancient Egypt, Israel, and Greece, in Byzantine cultures from about the 8th century, in India, and in Coptic and Jewish communities of the Near and Middle East to the present day), especially, it would seem, in cultures lacking musical notation. Chironomy is often used today in the teaching of school children, and it has been used as a supplement to musical notation in the teaching and conducting of Gregoriant chant.

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Pictorial evidence from as late as the 11th century shows that some instructors of liturgical chant reserved their right hands for chironomy and grasped with their left hands a staff that was both a token of authority and and instrument of discipline (Kienle, 1885).