hydroxylation

This term is a highly specialized technical noun used almost exclusively within organic chemistry, biochemistry, and pharmacology. It describes a specific chemical modification where a hydrogen atom is replaced by a hydroxyl group, often catalyzed by enzymes such as cytochrome P450 in biological systems.

Because it describes a specific chemical process or reaction, it is typically treated as an uncountable noun in scientific literature. It is rarely pluralized unless referring to multiple distinct types of hydroxylation reactions occurring at different positions on a molecular structure.