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 team investigated nanotubes functionalized with hydroxyl (‒OH), carboxyl (‒COOH), and amine (‒NH₂) groups to determine which surface chemistry performed best. — Muskan Bhatia, Interesting Engineering, 4 Nov. 2026

In 2025, Swift detected a compound called hydroxyl on the interstellar object 3I/ATLAS, indicating the presence of water. — Mary Ogborn, The Conversation, 4 Nov. 2026

Water essentially acts as a catalyst that spontaneously creates particles known as hydroxyl radicals, unstable molecules linked to aging and disease. — Michael Hawthorne, Chicago Tribune, 22 Oct. 2026

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