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REFERENCE

thermal

adj. · n.
US //ˈθɝməɫ// UK //θˈɜːməl// ther·mal
  1. 1 related to heat (adj.)
    B2 Upper Intermediate Technical Science

    relating to heat or temperature.

    pertaining to heat, temperature, or the movement of heat energy.

    Example

    The scientists measured the thermal energy produced by the chemical reaction.

    Example

    The spacecraft was equipped with a specialized shield to withstand the extreme thermal stress of atmospheric reentry.

  2. 2 keeping you warm (adj.)
    B2 Upper Intermediate

    designed to keep you warm by trapping heat, especially clothes.

    providing efficient thermal insulation to maintain body temperature in cold environments.

    Example

    You should wear thermal underwear if you are going skiing in the mountains.

    Example

    The hikers invested in high-quality thermal layers to ensure they remained warm during the overnight trek across the glacier.

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  1. 3 rising air (n.)
    C1 Advanced Technical

    a column of rising warm air that birds and gliders use to stay high in the sky.

    a column of rising air in the lower atmosphere created by the uneven heating of the earth's surface.

    Example

    The eagle circled higher and higher as it caught a strong thermal.

    Example

    The glider pilot searched for a thermal over the sun-baked fields to gain enough altitude for the return journey.

    • updraft
    • convection current
  2. 4 heat-sensing camera (n.)
    C1 Advanced Technical Military

    a type of camera or sensor that sees heat instead of light.

    an infrared imaging device or sensor used to detect heat signatures, often in low-visibility conditions.

    Example

    The rescue team used a thermal to find the lost hikers in the dark woods.

    Example

    The surveillance drone was equipped with a high-resolution thermal to detect movement through the dense forest canopy at night.

Origin

From French thermal, from New Latin thermalis, from Ancient Greek θέρμη (thérmē, “heat”), from Proto-Indo-European gʷʰer- (“to heat, warm”).

Word family

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