furnace

furnace — noun

1. a very hot enclosed chamber or structure used in factories and industrial settin

1.nounB2
Definition

a very hot enclosed chamber or structure used in factories and industrial settings for melting metals, making glass, or burning waste at extremely high temperatures

Example

Karim watched as the factory workers poured molten iron from the furnace into large moulds.

The old furnace in the glassblowing workshop glowed red-hot throughout the night.

collocation: glowed red-hot for extreme heat

Common collocations
  • blast furnace
  • electric furnace
  • furnace lining
  • furnace operator
  • furnace slag
  • open-hearth furnace
Synonyms
  • kiln

    for pottery, bricks, or cement — not for metal melting or waste burning

  • smelter

    specifically for extracting metal from ore, not for general high-heat processing

  • incinerator

    only for burning waste, not for melting or refining materials

Grammar Patterns

a/an + furnace

furnace + noun (attributive)

Usage Note

Often found in compound nouns that name specific furnace types: blast furnace (for iron production), electric arc furnace (for steelmaking), or kiln (for pottery and cement). This industrial sense is less frequent in everyday conversation than the building-heating sense.

Common Mistakes

The home furnace melted the steel.
The industrial furnace in the factory melted the steel.
Only industrial furnaces reach the extreme temperatures needed to melt metal; a home furnace heats air or water to much lower temperatures.

2. a device that burns fuel or uses electricity to provide warmth to a building, ty

2.nounB1
Definition

a device that burns fuel or uses electricity to provide warmth to a building, typically by heating air or water that moves through pipes, vents, or radiators

Example

The technician arrived to repair the furnace before the winter cold set in.

Adisa checked the furnace filter every month to keep the heating system running well.

collocation: furnace filter + monthly routine

Common collocations
  • furnace filter
  • furnace repair
  • gas furnace
  • furnace replacement
  • electric furnace
  • furnace technician
Synonyms
  • boiler

    heats water for radiators, more common in British English; a furnace typically heats air for duct-based systems

  • heater

    more general term for any device that produces warmth, often smaller or portable

Antonyms
  • air conditioner

    cools a building instead of heating it; the opposite seasonal appliance

Grammar Patterns

a/an + furnace

the + furnace

furnace + noun (attributive)

Usage Note

This sense is more common in American English. In British English, 'boiler' is typically used instead when the system heats water for radiators. 'Furnace' in this sense refers specifically to the heat-producing unit, not the whole heating system. The metaphorical simile 'like a furnace' (meaning very hot) is common in informal speech: 'This room is like a furnace!'

Common Mistakes

I turned on the furnace to cook dinner.
I turned on the furnace to warm the house.
A building furnace heats indoor air or water; it is not the same as a stove or oven for cooking.

Synonym discussion

Sense: noun/2

'Furnace' and 'boiler' are both central heating devices, but they work differently: a furnace heats air that moves through ducts, while a boiler heats water for radiators or underfloor pipes. 'Furnace' is the standard term in American English for home air-heating systems; 'boiler' is more common in British English. 'Heater' is a broad term covering anything from a small portable electric unit to a wall-mounted gas device — it is less specific and generally refers to smaller, sometimes portable appliances. 'Heating system' is the widest term, referring to the entire setup including the furnace or boiler, pipes or ducts, and controls. For example: 'Their gas furnace broke down midwinter, so they called a technician to fix it.' 'The boiler wasn't producing enough hot water for the radiators.' 'She bought a small electric heater for her desk at work.'

furnace ↗boilerheater ↗heating system

Common collocations

Nouns

  • furnace temperature
  • furnace heat
  • furnace system
  • furnace door

Phrases

  • like a furnace

Prepositions

  • in a/the furnace
  • into a/the furnace
  • out of a/the furnace

Etymology

LatinOld FrenchEnglish

The word 'furnace' comes from Old French 'fornais', meaning 'oven' or 'kiln', which traces back to Latin 'fornax' — a structure for heating or baking. The Latin root 'formus' means 'warm', placing 'furnace' in the same ancient Indo-European family as 'thermal' and 'thermometer', all from the root for 'heat' or 'warmth'.