furnace

noun

fur·​nace ˈfər-nəs 

: an enclosed structure in which heat is produced (as for heating a house or for reducing ore)

Examples of furnace in a Sentence

Recent Examples on the Web

The furnace produced more than 800 cannons during the war, and the gunpowder and cannonballs used to fire at British troops were made in villages throughout Connecticut. —Staff Report, Hartford Courant, 27 Apr. 2026

These units — available for gas and oil furnace systems and heat pumps — are sold at home centers, hardware stores and online. —Tribune Content Agency, Baltimore Sun, 27 Apr. 2026

Leaving the furnace running protects your pipes from freezing and also reduces moisture problems in your home. —Brandee Gruener, Southern Living, 24 Apr. 2026

Geothermal is four times more efficient than a boiler or furnace and twice as efficient as an air-source heat pump. —Lew Sichelman, Miami Herald, 23 Apr. 2026

Word History

Etymology

Middle English fourneyse, fornes, furneis "oven, kiln, furnace," borrowed from Anglo-French furneis, fornays, fornaise (continental Old French forneis —attested once as masculine noun— fornaise, feminine noun), going back to Latin fornāc-, fornāx (also furnāx) "furnace, oven, kiln (for heating baths, smelting metal, firing clay)," from forn-, furn-, base of furnus, fornus "oven for baking" + -āc-, -āx, noun suffix; forn- going back to Indo-European *g^whr̥-no- (whence also Old Irish gorn "piece of burning wood," Old Russian grŭnŭ, gŭrnŭ "cauldron," Russian gorn "furnace, forge," Bosnian-Croatian-Serbian gŕno "coals for heating iron at a smithy," Sanskrit ghṛṇáḥ "heat, ardor"), suffixed derivative of a verbal base *g^wher- "become warm" — more at therm

Note: The variation between -or-, the expected outcome of zero grade, and -ur- in Latin has been explained as reflecting a rural/dialectal change of o to u, borrowing from Umbrian, or the result of a sound change of uncertain conditioning; see most recently Nicholas Zair, "The origins of -urC- for expected -orC- in Latin," Glotta, Band 93 (2017), pp. 255-89.

First Known Use

13th century, in the meaning defined above

Phrases Containing furnace

• blast furnace
• reverberatory furnace

Rhymes for furnace

• externus

Kids Definition

furnace

noun

fur·​nace ˈfər-nəs 

: an enclosed structure in which heat is produced (as for heating a house or melting metals)