A layer in a large body of water, such as a lake, that sharply separates regions differing in temperature, so that the temperature gradient across the layer is abrupt.(noun)
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.
Use "thermocline" in a sentence
"In between the two layers, there is a narrow zone called the thermocline where the temperature of the water changes rapidly."
"The thin yellow line is probably the thermocline, which is the place where the warm water and cold water meet."
"The ocean is not really one ocean, but two -- a top and bottom layer, with a boundary layer approximately one kilometer below the ocean surface, called the thermocline, through which very little vertical transport takes place."