H. P. Blavatsky

Od. From odos, “passage”, or passing of that force which is developed by various minor forces or agencies such as magnets, chemical or vital action, heat, light, &c. It is also called “odic” and “odylic force”, and was regarded by Reichenbach and his followers as an independent entitative force — which it certainly is — stored in man as it is in Nature.

Source: H. P. Blavatsky, The Theosophical Glossary, art. Od