Definition of "hydrothermal" []

• Of or relating to hot water. (adjective)
• Geology Of or relating to hot magmatic emanations rich in water. (adjective)
• Geology Of or relating to the rocks, ore deposits, and springs produced by such emanations. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In May an arm of the Chinese government submitted plans to explore the seafloor around an underwater ridge in the Indian Ocean near Madagascar, where hot springs in the ocean bottom called hydrothermal vents have created deposits containing gold, silver, copper, nickel, cobalt, and tellurium (used in computers, CDs, and DVDs)."
• "The most likely place for it to occur, he believes, is at miniature undersea volcanoes called hydrothermal vents, where the ingredients and conditions are just right for energy-harnessing chemical machinery to develop."
• "Among other things, the researchers on board Dayang Yihao located rich deposits of copper, lead and zinc, associated with hot springs called hydrothermal vents that are often found near mid-ocean ridges."