Oscilla

Oscilla, a word applied in Latin usage to small figures, most commonly masks or faces, which were hung up as offerings to various deities, either for propitiation or expiation, and in connection with festivals and other ceremonies. It is usually taken as the plural of oscillum (diminutive of os), a little face. As the oscilla swung in the wind, oscillare came to mean to swing, hence in English oscillation, the act of swinging backwards and forwards, periodic motion to and fro, hence any variation or fluctuation, actual or figurative. For the scientific problems connected with oscillation see Mechanics and Oscillograph.