lye

American  

[lahy] / laɪ /

noun

Chemistry.

• lyes
  plural

1. a highly concentrated, aqueous solution of potassium hydroxide or sodium hydroxide.

2. any solution resulting from leaching, percolation, or the like.

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lye British  

/ laɪ /

noun

1. any solution obtained by leaching, such as the caustic solution obtained by leaching wood ash

2. a concentrated solution of sodium hydroxide or potassium hydroxide

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lye Scientific  

/ lī /

1. A strong alkaline solution or solid of potassium hydroxide or sodium hydroxide, made by allowing water to wash through wood ashes. It is used to make soap and drain and oven cleaners. Chemical formula: KOH or NaOH.

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Other Word Forms

Noun Inflected Forms

• lyes
  plural

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Etymology

Origin of lye

First recorded before 900; Middle English lie, ley, Old English lēag; cognate with Dutch loog, German Lauge “lye,” Old Norse laug “warm bath”; see lave ¹

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Explanation

Lye is an alkaline solution that's used for cleaning. If you were a maid about 200 years ago, you probably cleaned the chamber pots with lye. Lye is an old cleaning product and an old word too. It comes from the Old English léag, which is related to the root for "wash" in our word lather. Lye is still used to make soap, but you probably won't come across the word except in old novels. If you become a historical re-enactor, say goodbye to body wash and hello to lye.

Example Sentences

See Examples For:

lye lyes

The process uses hot water mixed with an alkaline lye solution, so it’s more environmentally friendly than standard cremation, and usually more expensive.

From Los Angeles Times ● Jul. 23, 2025

The prohibition against soap comes from a time when all soap was made with lye, which could eat through a patina in minutes.

From Seattle Times ● Apr. 13, 2024

To make the humanmade version, the team first softened thin strips of oak by boiling them with lye and sodium sulfite.

From Science Magazine ● Feb. 15, 2023

Classic pretzels are made with the help of food-grade lye, which is responsible for a pretzel's characteristic chew and deeply brown exterior.

From Salon ● Oct. 10, 2022

A nun at St. Agnes Academy had once washed Hazel’s mouth with lye soap for saying something very similar, so she wasn’t sure how to respond.

From "The Son of Neptune" by Rick Riordan

If a Ball be stopp’d by any Person, Horse, Dog or anything else, The Ball so stop’d must be play’d where it lyes.

From Golf Digest ● Mar. 31, 2020

If a ball be stopp’d by any person, horse, dog, or anything else, the ball so stopp’d must be play’d where it lyes.

From New York Times ● Mar. 13, 2018

He whose ball lyes farthest from the hole is obliged to play first.

From New York Times ● Mar. 13, 2018

But there are many Smatterers and ignorant Fellows, that would fain reconcile the ancient Writers, and excuse these lyes; not seeing what damage they bring to the Common-wealth of Learning.

From "The Invention of Science" by David Wootton

Here lyes the body of William Wheatley, ob. 10th Nov. 1683.

From William Shakespere, of Stratford-on-Avon His Epitaph Unearthed, and the Author of the Plays run to Ground by Scott Surtees

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