thermal thermal /ˈθɝːməl/

adjective

1. () Relating to or associated with heat  ( caloric , thermic , thermal )
   relating to or associated with heat
    Thermal movements of molecules
   thermal movements of molecules
    Thermal capacity
   thermal capacity
    Thermic energy
   thermic energy
    The caloric effect of sunlight
   the caloric effect of sunlight
   
2. Caused by or designed to retain heat  ( thermal )
   caused by or designed to retain heat
    A thermal burn
   a thermal burn
    Thermal underwear
   thermal underwear
   
3. Of or relating to a hot spring  ( thermal )
   of or relating to a hot spring
    Thermal water
   thermal water
   

noun

1. Rising current of warm air  ( thermal )
   rising current of warm air
    Birds often utilize thermals, the rising currents of warm air, to soar effortlessly in the sky.
   Birds often utilize thermals, the rising currents of warm air, to soar effortlessly in the sky.