lye

American  

[lahy] / laɪ /

noun

Chemistry.

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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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

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

Logan Lye has cerebral palsy and learning disabilities.

From BBC • Apr. 5, 2026

“In a way to glorify women’s golf I made a comparison by comparing it to another sport that maybe isn’t so successful,” Lye said Tuesday.

From Washington Times • Feb. 9, 2022

Who knew That the smallest of bases Could make a Big Lye!

From Washington Post • Oct. 14, 2021

She fired the ball to catcher Aubree Munro, who tagged pinch-runner Joey Lye out at the plate.

From Fox News • Jul. 22, 2021

Lye still, lye still, thou little Musgrave, And huggell me from the cold; Tis nothing but a shephards boy, A driving his sheep to the fold.

From English and Scottish Ballads, Volume II (of 8) by Various