flue

¹ American  

[floo] / flu /

noun

1. a passage or duct for smoke in a chimney.

2. any duct or passage for air, gas, or the like.

3. a tube, especially a large one, in a fire-tube boiler.

4. Music.

   1. flue pipe.

   2. Also called windway.  a narrow slit in the upper end of an organ pipe through which the air current is directed.

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flue ² American  

[floo] / flu /

noun

1. downy matter; fluff.

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flue ³ American  

[floo] / flu /

Or flew

noun

1. a fishing net.

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flue ¹ British  

/ fluː /

noun

1. a shaft, tube, or pipe, esp as used in a chimney, to carry off smoke, gas, etc

2. music the passage in an organ pipe or flute within which a vibrating air column is set up See also flue pipe

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flue ² British  

/ fluː /

noun

1. loose fluffy matter; down

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flue ³ British  

/ fluː /

noun

1. a type of fishing net

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flue ⁴ British  

/ fluː /

noun

1. another word for fluke 1 fluke 1

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Other Word Forms

• flued adjective

Etymology

Origin of flue¹

First recorded in 1555–65; earlier flew; of uncertain origin; perhaps from Old English flēwsa “a flowing, flux,” the form flews being taken as plural

Origin of flue²

First recorded in 1580–90; of uncertain origin; perhaps from Old English flug- (in flugol “swift, fleeting”); perhaps from Flemish Dutch vluwe, from French velu “hairy, downy”; velvet ( def. )

Origin of flue³

First recorded in 1350–1400; Middle English flue, flowe, flew, from Middle Dutch vl(o)uwe “fishing net”; akin to Old English flōwan flow ( def. )

Explanation

When smoke flows out of a chimney, it moves through a narrow opening called a flue. Before you light a fire in the fireplace, make sure the flue is open! Don't mistake flue for its homonym, flu — rather than an illness, a flue is a duct or pipe that's connected to a stove, heater, furnace, or fireplace. Smoke or gas can flow freely through the flue, which allows the appliance to work properly and vents any nasty exhaust away from people. Experts disagree about the origin of this word, but many trace it back to a Germanic root meaning "to flow."

Example Sentences

A generation or so ago, an open stair like this would have been restricted to two stories to ensure it didn’t act as a flue during a fire.

From The Wall Street Journal • Mar. 20, 2026

Their goal was to create a device capable of handling flue gas as it is actually produced and converting even small amounts of captured CO2 into a valuable product.

From Science Daily • Jan. 29, 2026

However, sounds from things like flue organ pipes or flutes, which are propagated through air, would be pitched higher than Earth.

From Salon • Jun. 3, 2025

The home’s boiler was serviced in July this year, a flue was replaced, and it passed checks, the BBC understands.

From BBC • Oct. 23, 2024

In a stove flue no longer used, she had hidden a little meal bag which she called her treasure.

From "The Bluest Eye" by Toni Morrison

Related Words

• chimney
• duct