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In days gone by, much of the male population of the northern states in the cold months would wear a garment of thermal underwear covering the entire body, called a union suit. Union suits kept sodbusters, cowboys, and townsfolk alike not only warm but also itchy and a little on the smelly side (back when bathing once a week was considered the height of cleanliness). Thermal imaging is photography that captures "heat pictures"--rather than ordinary light pictures--of objects. And thermal pollution occurs when industrial water use ends up warming a river in a damaging way. Small-plane pilots use thermal as a noun for a warm updraft, often over a plowed field or desert, that lifts their wings, just as it enables hawks to soar upward without moving their wings.
Examples of thermal in a Sentence
David Blekhman, Forbes.com, 9 July 2025
Winds look generally light and slope driven in the extended with a preference towards Northeast flow night and morning hours as a thermal trough tries to develop over the region.
—Ca Wildfire Bot, Sacbee.com, 9 July 2025
Charlie Eccleshare, New York Times, 31 May 2025
It has been recorded flying at heights of up to 24,000 feet, gliding on thermals.
—Scott Travers, Forbes.com, 14 June 2025
See All Example Sentences for thermal
Cite this Entry
“Thermal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thermal. Accessed 15 Jul. 2025.
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