Of, relating to, using, producing, or caused by heat.(adjective)
Intended or designed in such a way as to help retain body heat: thermal underwear. (adjective)
A rising current of warm air.(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 "thermal" in a sentence
"His use of the term thermal equilibrium between the atmosphere and surface is highly ambiguous."
"I hope they did more than enough testing in thermal vac and every other way to be sure it will function."
"Also, heat radiation affects the polar caps more than one way or maybe my ignorance in thermal-dynamics is too apparent."