borax

¹ American  

[bawr-aks, -uhks, bohr-] / ˈbɔr æks, -əks, ˈboʊr- /

noun

plural

boraxes, boraces

1. a white, water-soluble powder or crystals, hydrated sodium borate, Na 2 B 4 O 7 ⋅10H 2 O, occurring naturally or obtained from naturally occurring borates; tincal: used as a flux, cleansing agent, in the manufacture of glass, porcelain, and enamel, and in tanning.

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borax ² American  

[bawr-aks, -uhks, bohr-] / ˈbɔr æks, -əks, ˈboʊr- /

noun

1. cheap, showy, poorly made merchandise, especially cheaply built furniture of an undistinguished or heterogeneous style.

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borax British  

/ ˈbɔːræks /

noun

1. Also called: tincal.  a soluble readily fusible white mineral consisting of impure hydrated disodium tetraborate in monoclinic crystalline form, occurring in alkaline soils and salt deposits. Formula: Na 2 B 4 O 7 .10H 2 O

2. pure disodium tetraborate

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borax Scientific  

/ bôr′ăks′ /

1. A white, crystalline powder and mineral used as an antiseptic, as a cleansing agent, and in fusing metals and making heat-resistant glass. The mineral is an ore of boron and also occurs in yellowish, blue, or green varieties. Chemical formula: Na ₂ B ₄ O ₇ ·10H ₂ O.

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Etymology

Origin of borax¹

1350–1400; < Medieval Latin ≪ dialectal Arabic būraq < Middle Persian būrag; replacing Middle English boras < Middle French < Medieval Latin borax

Origin of borax²

An Americanism dating back to 1940–45; of uncertain origin

Explanation

Borax is a mineral that's often used in a powdered form as a cleanser or water softener. Borax is another name for sodium borate, a chemical salt that was discovered in 8th-century Tibet. Medieval ceramicists used borax in their pottery glazes, and in modern times it's been used to make glass. Borax can also act as a fire retardant in wood and textiles. In household use, borax is still sometimes added to a load of laundry or worked into soil as a fertilizer. It is widely attested that the name borax comes from the Persian word būrah.

Example Sentences

In the Chicago of my youth, a borax man was an especially slick salesman, aggressive and relentless, usually specializing in home-improvement products.

From The Wall Street Journal • Dec. 18, 2025

The fire, one of two that day, occurred just after midnight April 4 behind the Borax Museum and destroyed a wooden wagon used to transport borax out of Death Valley in the late 1800s.

From Los Angeles Times • May 15, 2024

Experts say social media users appear to be conflating boron, a naturally occurring mineral, with borax, which is also naturally occurring and is produced when boron is combined with sodium, hydrogen and oxygen.

From Seattle Times • Jul. 28, 2023

But while borax is naturally occurring, this isn't a guarantee of safety.

From Salon • Jul. 26, 2023

Using borax, water, and pipe cleaners, we made our own crystals.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas