Definition of "thermal"

thermal

/ˈθɝməl/

adjective
not comparable
1. Pertaining to heat or temperature.
  Quotations
  Similar studies of rats have employed four different intracranial resorbable, slow sustained release systems—surgical foam, a thermal gel depot, a microcapsule or biodegradable polymer beads.
  2013 May-June, Charles T. Ambrose, “Alzheimer’s Disease”, in American Scientist, volume 101, number 3, page 200
2. (fabric) Providing efficient insulation so as to keep the body warm.
3. Caused or brought about by heat.
4. (stone) Having a rough finish by treatment with a blow-torch.
noun
plural thermals
1. (meteorology) A column of rising air in the lower atmosphere created by uneven heating of Earth's surface.
  Quotations
  The hawk had mounted its thermal by the time he got to the yard, flapping its wings violently against the updraft.
  2019, Chigozie Obioma, An Orchestra of Minorities, Abacus (2019), page 91
verb
third-person singular simple present thermals, present participle thermaling or thermalling, simple past and past participle thermaled or thermalled
1. (stone) To create a rough finish on stone by treating it with a high-temperature blow-torch.
2. (gliding, often in the present participle) To fly an unpowered aircraft in a (thermal) column of rising air.