hydroxyl

noun

hy·​drox·​yl hī-ˈdräk-səl 

1

: the chemical group, ion, or radical OH that consists of one atom of hydrogen and one of oxygen and is neutral or negatively charged

2

: hydroxide sense 1

hydroxylic

ˌhī-ˌdräk-ˈsi-lik 

adjective

Examples of hydroxyl in a Sentence

Recent Examples on the Web

Seconding this theory, Ryugu also shows signs of being covered in hydroxyl, a material made up of hydrogen and oxygen. — Korey Haynes, Discover Magazine, 19 Mar. 2019

Whitening strips blend both the natural process of oil pulling with hydrogen peroxide to safely and effectively release oxygen and hydroxyl free radicals for a brighter, whiter smile in as soon as 14 days. — ABC News, 1 May 2026

Mergers like this trigger bouts of intense star formation, as well as creating the physical conditions that allow the hydroxyl molecules to amplify radio emission. — Robert Lea, Space.com, 30 Mar. 2026

After each lightning flash, the researchers found the concentrations of hydroxyl and hydroperoxyl increased by thousands of parts per trillion, Science News reports. — Elizabeth Gamillo, Smithsonian Magazine, 4 May 2021

Word History

Etymology

hydr- + ox- + -yl

First Known Use

1869, in the meaning defined at sense 1

Rhymes for hydroxyl

• glyoxal
• methoxyl
• coxal
• voxel
• pyridoxal

Kids Definition

hydroxyl

noun

hy·​drox·​yl hī-ˈdräk-səl 

: a chemical group or ion that consists of one atom of hydrogen and one of oxygen

Medical Definition

hydroxyl

noun

hy·​drox·​yl hī-ˈdräk-səl 

1

: the chemical group or ion OH that consists of one atom of hydrogen and one of oxygen and is neutral or positively charged

2

: hydroxide sense 1

hydroxylic

ˌhī-ˌdräk-ˈsil-ik 

adjective