thermal
thermal — adjective
1. involving or produced by heat energy — for example, thermal power stations that
involving or produced by heat energy — for example, thermal power stations that burn fuel to generate electricity, or thermal insulation that stops heat from escaping a building.
The thermal power station near Hiro's town burns coal to make electricity for local homes.
thermal + noun: power station / insulation / energy
Noor wrapped the pipes in thermal material to stop them from freezing during winter.
Mayumi wrapped a rescued bird in a thermal blanket on the way to the vet.
thermal + noun: blanket (for heat retention)
The car's seats have a thermal heating system that warms up on very cold mornings.
Talia borrowed a thermal camera to find water pipes hidden behind her living room wall.
thermal + noun: camera / imaging / scanning
- thermal energy
- thermal power
- thermal insulation
- thermal mass
- thermal radiation
- thermal imaging
- thermal camera
- heat-related
less technical, used in general contexts
- heat
used as a noun modifier ('heat energy'), not equivalent as an adjective
- cold
describes the absence of heat rather than a direct opposite of the adjective thermal
Grammar Patterns
thermal + noun
Usage Note
Often appears before a noun as a technical or semi-technical term — common compounds include thermal energy, thermal insulation, thermal conductivity, and thermal imaging. In everyday language, thermal most often describes clothing or building materials rather than abstract heat concepts.
Common Mistakes
2. made from a special material that traps body warmth, helping you stay warm in co
made from a special material that traps body warmth, helping you stay warm in cold weather — commonly used for clothing, blankets, curtains, and bedding.
Vivek bought a thermal jacket for his hiking trip in the mountains last month.
thermal + jacket / socks / underwear
Sade wears thermal socks every morning when she walks her dog in the snow.
The children's thermal pyjamas kept them warm even after the heating stopped working at night.
Dylan packed his thermal underwear for the camping trip in the cold forest.
thermal + underwear — the most common compound in this sense
Adina bought thermal curtains for her bedroom to keep the cold air out during winter.
Construction workers on the new hospital site wore thermal gloves all through the cold season.
thermal + article of clothing: gloves / socks / jacket
- thermal underwear
- thermal socks
- thermal jacket
- thermal vest
- thermal blanket
- thermal curtains
- thermal clothing
- thermal base layer
- lightweight
describes thin clothing without insulation
- breathable
describes fabric that lets air through, opposite of trapping heat
Grammar Patterns
thermal + article of clothing
Usage Note
Only applies to items specifically designed with insulating material to retain body heat. An ordinary warm woollen jumper is 'warm' but not 'thermal' unless it has a special insulating lining. Thermal clothing is often worn as a base layer beneath other garments.
Common Mistakes
3. relating to water that has been naturally warmed underground by the earth's inte
relating to water that has been naturally warmed underground by the earth's internal heat — used to describe hot springs, pools, spa treatments, or resorts that use geothermally heated water.
The hotel in Japan has a thermal pool fed by hot springs from deep underground.
thermal + pool / bath / spring / spa
Christopher went to a thermal spa in Iceland with water from volcanic rock deep underground.
Thermal springs in New Zealand attract visitors who bathe in the warm mineral water.
The town built a public thermal bath with water from the heated spring.
Noor booked a weekend at a thermal resort with outdoor hot pools and steam rooms.
collocation: thermal resort — a hotel complex based around hot springs
- thermal spring
- thermal bath
- thermal pool
- thermal water
- thermal spa
- thermal resort
- thermal treatment
- thermal mud
- geothermal
more technical — refers specifically to heat from the earth's interior
- hot-spring
colloquial compound, used as an adjective ('hot-spring bath')
- cold
describes water at normal ground temperature
Grammar Patterns
thermal + water/bath/spring/spa
Usage Note
Almost always appears before a noun describing a water feature or facility. The thermal spring (geological formation) and the thermal bath (man-made pool) are the most common collocations. Distinguish from sense 1 (HEAT-RELATED) — sense 3 is specifically about geothermally heated water, not heat in general.
Common Mistakes
4. relating to how a physical material behaves or changes depending on its temperat
relating to how a physical material behaves or changes depending on its temperature — used in science to describe properties such as thermal expansion, thermal motion, thermal equilibrium, and thermal conductivity.
In science class, Maeve measured a metal rod's thermal expansion as it got hot.
thermal + noun: expansion / energy / motion / equilibrium
An ice cube on the table absorbed thermal energy from the air and melted into a puddle.
thermal energy — heat transfer in a concrete scene
Christopher learned about thermal conductivity when he touched a metal spoon left in hot soup.
In science class, Dario watched gas particles move faster on the screen when the heater turned on.
thermal motion — demonstrated through a simulation in class
Mira studied how two objects reach thermal equilibrium when they touch each other.
thermal equilibrium — a key physics concept at this sense
- thermal energy
- thermal motion
- thermal expansion
- thermal conductivity
- thermal equilibrium
- thermal radiation
- thermal capacity
- thermal efficiency
- thermodynamic
more specific — describes heat-to-work conversion and system behaviour
- caloric
historical term for heat-related, now rare in modern physics
Grammar Patterns
thermal + noun (property/behaviour)
Usage Note
A technical sense used primarily in physics and materials science. Each compound (thermal expansion, thermal equilibrium, thermal motion) is a distinct scientific term with a precise definition. Not used in everyday conversation. Distinguish from sense 1 (HEAT-RELATED) — sense 4 describes properties and behaviours governed by temperature, not simply things connected with heat.
Common Mistakes
thermal — noun
1. a column of heated air that moves upward from the ground, often used by birds an
a column of heated air that moves upward from the ground, often used by birds and glider pilots to rise without spending their own energy.
Hawks circle in thermals high above the valley while searching for food on the ground.
birds ride thermals to gain height
Glider pilots look for thermals above warm fields to stay in the air longer.
On hot summer days, thermals rise from parking lots and create bumps for light planes.
The eagle caught a strong thermal and rose high without flapping its wings.
verb + thermal: catch a thermal / ride a thermal / find a thermal
Paragliders depend on thermals to stay in the air for hours during good weather conditions.
- ride a thermal
- catch a thermal
- find a thermal
- use a thermal
- look for thermals
- strong thermal
- warm thermal
- downdraft
a downward moving current of air
Grammar Patterns
thermal + verb (rise/form/carry)
verb + thermal (ride/catch/find)
Usage Note
Most commonly used in the plural (thermals). Frequently paired with verbs such as ride, catch, find, use, or look for. The singular (a thermal) is used when referring to a specific updraught. Not used for indoor or artificial warm air currents.
Common Mistakes
2. items of clothing made from special fabric that holds body heat close to the ski
items of clothing made from special fabric that holds body heat close to the skin, usually worn as a base layer under other clothes in cold weather.
Nikos wore thermals under his shirt when he went skiing in the French Alps.
wear thermals under [+ outer clothing]
The outdoor shop sells thermals for workers who spend long hours outside in freezing weather.
Manuela always packs extra thermals when visiting her family in the cold countryside.
The children put on their thermals before going out to build a snowman.
put on thermals / pack thermals / buy thermals
Dylan bought a new pair of thermals for his winter hike through the national park.
a pair of thermals — count usage
- wear thermals
- pack thermals
- buy thermals
- a pair of thermals
- thick thermals
- thermal base layer
- long johns
informal — specifically refers to thermal underwear for the legs and torso
- base layer
modern term used in sportswear for any close-fitting first layer
- thermal underwear
more formal, less common than simply 'thermals'
Grammar Patterns
wear thermals
a pair of thermals
pack thermals
Usage Note
Almost always used in the plural (thermals), even when referring to a single garment. You can say 'a pair of thermals' or 'some thermals'. In retail contexts, singular (a thermal) is sometimes used informally to mean a single thermal garment, but this is less common. Refers specifically to insulating base-layer clothing, not to any warm garment.
Common Mistakes
Word family
- thermallyadverbB2
- thermometernounB1
- thermostatnounB2
- geothermaladjectiveC1
- thermodynamicsnounC1
- hypothermianounC1
- thermosnounB1
Synonym discussion
Sense: adjective/1
Thermal describes something directly connected with heat — a thermal power station burns fuel to produce heat for electricity, and thermal insulation traps heat inside a building. Heat-related is a looser, non-technical phrase that can cover any association with heat (heat-related illness, heat-related costs) without the precision of thermal. Thermodynamic is a more specialised science term that describes the relationship between heat and other forms of energy, especially in engines and chemical systems. Warm, by contrast, describes a moderate temperature that feels comfortable to the touch — a warm jacket keeps you comfortable, but a thermal jacket keeps you warm through insulating material. In short: thermal is about heat as a physical quantity; warm is about personal comfort; thermodynamic is about heat energy conversion; and heat-related is a general catch-all phrase.
Common collocations
Adverbs
- thermally
Phrases
- thermal power station
- thermal imaging camera
- thermal expansion coefficient
- thermal equilibrium state
Etymology
The word thermal comes from the Greek word thermē, meaning 'heat'. This passed into Latin as thermae, which referred to hot baths or bathhouses in ancient Rome. English adopted thermal as a scientific adjective in the 1700s and later expanded it to describe insulating clothing and meteorological updraughts in the 1900s.