furnace
Americannoun
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a structure or apparatus in which heat may be generated, as for heating houses, smelting ores, or producing steam.
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a place characterized by intense heat.
The volcano was a seething furnace.
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Astronomy. Furnace, the constellation Fornax.
verb (used with object)
noun
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an enclosed chamber in which heat is produced to generate steam, destroy refuse, smelt or refine ores, etc
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a very hot or stifling place
Other Word Forms
Derived Forms
Etymology
Origin of furnace
First recorded in 1175–1225; Middle English furneis, furnais, from Old French fornais, fournais, from Latin fornāc- (stem of fornāx “kiln, oven”), akin to formus “warm”
Explanation
A furnace is an appliance that heats houses and buildings by burning fuel or circulating hot water. Your furnace might rumble in the basement, sending heat up through your house's radiators. Most houses in cold climates have a furnace, to warm their rooms during the chilly months of the year. Furnaces also have industrial uses, like burning trash or extracting ore from metal. If someone says, "It's as hot as a furnace in this classroom!" they mean that it's extremely hot. Furnace comes from the Old French fornaise, "oven," with the Latin root word fornacem, "oven or kiln."
Vocabulary lists containing furnace
Mockingbird
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Unit 4: Powerful Openings
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Unit 1, Words to Know
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Last week, the federal government said it "recognises the need for uninterrupted furnace operations" and is taking steps to manage supplies.
From BBC • Apr. 28, 2026
Maybe the furnace needs replacing, a medical bill arrives out of the blue, or an education expense catches you by surprise.
From MarketWatch • Apr. 23, 2026
You might go out to work and let the house cool down; then return home and fire up the furnace.
From BBC • Mar. 22, 2026
The gold-plated figure she’d won for “Fantastic Beasts” was warped and blackened by heat, its surface blistered and twisted like something pulled from a furnace.
From Los Angeles Times • Mar. 12, 2026
“Huh, it’s going to be as hot as the hell’s furnace, but at least it won’t rain,” he muttered aloud to himself.
From "Redwall" by Brian Jacques
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
