[thur-muh l]
See more synonyms for thermal on
  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.
  1. Meteorology. a rising air current caused by heating from the underlying surface, especially such a current when not producing a cloud.
  2. thermals. thermal underwear.

Origin of thermal

First recorded in 1750–60; therm- + -al1
Related formsther·mal·ly, adverbhy·per·ther·mal, adjectivehy·per·ther·mal·ly, adverbnon·ther·mal, adjectivenon·ther·mal·ly, adverb

thermal underwear

  1. underwear designed to retain body heat in cold temperatures.
Also called thermals. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for thermals

thermals, woolens

Examples from the Web for thermals

Contemporary Examples of thermals

British Dictionary definitions for thermals


  1. Also: thermic (ˈθɜːmɪk) of, relating to, caused by, or generating heat or increased temperature
  2. hot or warmthermal baths; thermal spring
  3. (of garments or fabrics) specially designed so as to have exceptional heat-retaining properties
  1. meteorol a column of rising air caused by local unequal heating of the land surface, and used by gliders and birds to gain height
  2. (plural) thermal garments, esp underclothes
Derived Formsthermally, 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

Word Origin and History for thermals



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

thermals in Medicine


  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.

thermals in Science


  1. Relating to heat.
  1. 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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.