che·mo·syn·the·sis 
(kē′mō-sĭnthĭ-sĭs, kĕm′ō-)
(kē′mō-sĭnthĭ-sĭs, kĕm′ō-)n.
The synthesis of organic compounds by certain bacteria, especially in deep-sea hydrothermal vents, using energy obtained from the chemical oxidation of simple inorganic compounds. Chemosynthesis is thought to have been used by the first forms of life on Earth.
che′mo·syn·thetic (-sĭn-thĕtĭk) adj.
che′mo·syn·theti·cal·ly adv.