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

The polystyrene powder and water mixture contained hydroxyl radicals, a highly reactive ROS. — Jacek Krywko, ArsTechnica, 15 Oct. 2026

Fluorine is then released into the water as fluoride ions, while hydroxyl radicals and hydroxide ions help sever carbon-carbon bonds in the remaining molecular chains. — Alexandra Harrell, Footwear News, 14 Oct. 2026

Further tests showed that the plastic surfaces were producing hydroxyl free radicals, a highly reactive form of oxygen, in the absence of light or added chemicals. — Emily Kay Votruba, EverydayHealth.com, 14 Oct. 2026

According to the researchers, the catalyst weakens excessive bonding between iron sites and hydroxyl intermediates, allowing the reaction to proceed more smoothly and reducing one of the major bottlenecks in zinc-air battery operation. — Neetika Walter, Interesting Engineering, 13 June 2026

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