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thermal

[thur-muh l] /ˈθɜr məl/
adjective
1.
Also, thermic. of, relating to, or caused by heat or temperature:
thermal capacity.
2.
of, relating to, or of the nature of thermae:
thermal waters.
3.
designed to aid in or promote the retention of body heat:
a thermal blanket.
noun
4.
Meteorology. a rising air current caused by heating from the underlying surface, especially such a current when not producing a cloud.
5.
thermals, thermal underwear.
Origin
1750-1760
1750-60; therm- + -al1
Related forms
thermally, adverb
hyperthermal, adjective
hyperthermally, adverb
nonthermal, adjective
nonthermally, adverb

thermal underwear

noun
1.
underwear designed to retain body heat in cold temperatures.
Also called thermals.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for thermals

thermal

/ˈθɜːməl/
adjective
1.
Also thermic (ˈθɜːmɪk). of, relating to, caused by, or generating heat or increased temperature
2.
hot or warm: thermal baths, thermal spring
3.
(of garments or fabrics) specially designed so as to have exceptional heat-retaining properties
noun
4.
(meteorol) a column of rising air caused by local unequal heating of the land surface, and used by gliders and birds to gain height
5.
(pl) thermal garments, esp underclothes
Derived Forms
thermally, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for thermals

thermal

adj.

1756, "having to do with hot springs," from French thermal (Buffon), from Greek therme "heat," from PIE *ghwerm-/*ghworm- "warm" (cf. Latin fornax "an oven, kiln," formus "warm," Old English wearm; see warm). Sense of "having to do with heat" is first recorded 1837. The noun meaning "rising current of relatively warm air" is recorded from 1933.

Online Etymology Dictionary, © 2010 Douglas Harper
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thermals in Medicine

thermal ther·mal (thûr'məl)
adj.

  1. Of, relating to, using, producing, or caused by heat.

  2. Intended or designed in such a way as to help retain body heat.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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thermals in Science
thermal
  (thûr'məl)   
Adjective  Relating to heat.

Noun  A usually columnar mass of warm air that rises in the lower atmosphere because it is less dense than the air around it. Thermals form because the ground surface is heated unevenly by the Sun. The air usually rises until it is in equilibrium with the air surrounding it.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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