The Collaborative International Dictionary
Hydrothermal \Hy`dro*ther"mal\, a. [Hydro-, 1 + thermal.]
Of or pertaining to hot water; -- used esp. with reference to the action of heated waters in dissolving, redepositing, and otherwise producing mineral changes within the crust of the globe.
of, pertaining to, or using the hot waters or steam found at special locations within the earth's crust; as, hydrothermal power generation.
Douglas Harper's Etymology Dictionary
Wiktionary
a. 1 of, or relating to hot water 2 (context geology English) of or relating to emanations of hot water that are rich in minerals, or to the rocks formed from them
Wikipedia
Usage examples of "hydrothermal".
The hydrothermal instrumentation in the two blisters on the sail keep us informed of the temperature differentials between the currents, and by sailing the Barracuda directly in the interface zone we are effectively shielded from detection.
Tony May is analyzing the genomes of archaebacterial species that inhabit the hot, anaerobic waters of hydrothermal vents and deep rocks, looking for highly conserved genes that may have belonged to the universal ancestor of all life on Earth.
The exhibits were devoted to Europan biota, most of which depended on the ecological niches of the hydrothermal vents, carefully reproduced here.
Now that they were looking at it from above, they could see that the hydrothermal vent actually had two plumes, one directly behind the other, their jets rising at right angles from the top of the mound.