Chironomia

Chironomia is the art of using gesticulations or hand gestures to good effect in traditional rhetoric or oratory. Effective use of the hands, with or without the use of the voice, is a practice of great antiquity, which was developed and systematized by the Greeks and the Romans. Various gestures had conventionalized meanings which were commonly understood, either within certain class or professional groups, or broadly among dramatic and oratorical audiences.
Gilbert Austin was a well-known author on chironomia. The article about him contains a summary of theories in chironomia.