What does acetyl mean?
Acetyl is a noun used almost exclusively in chemistry and biochemistry to name the univalent group CH₃CO–, which is derived from acetic acid by removing its hydroxyl portion. Because this fragment can attach to other atoms and molecules, it appears throughout organic chemistry as a building block: acetyl chloride, acetaldehyde, and acetylsalicylic acid (aspirin) all contain it. In living systems the acetyl group has special importance — acetyl coenzyme A carries acetyl units through central metabolism, and the addition of acetyl groups to proteins (acetylation) helps regulate gene activity. The term derives from 'acetic', ultimately tracing back to Latin acetum, meaning vinegar, reflecting the group's origin in the familiar sour acid. Though unfamiliar to most general readers, acetyl is fundamental to how chemists describe both industrial compounds and the chemistry of life itself.
nounThe univalent chemical group CH₃CO–, derived from acetic acid by removal of the hydroxyl group, that forms the basis of many organic compounds such as acetaldehyde and acetylcholine.
- The univalent radical CH₃CO–, derived from acetic acid, occurring as a substituent group in numerous organic compounds.
"The enzyme transfers an acetyl group onto the histone protein, altering gene expression."
"Acetylation adds an acetyl group to a molecule, often changing its biological activity."
"In the body, acetyl coenzyme A shuttles acetyl groups between metabolic pathways."
Aspirin's full chemical name is acetylsalicylic acid — so every tablet you swallow carries an acetyl group.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acetyl
The word acetyl was coined in the nineteenth century by German chemists, formed from 'acetic' with the suffix '-yl' used to denote a univalent radical derived from an acid. Its ultimate root is Latin acetum, meaning vinegar, the source also of 'acetic', 'acetate', and 'acetone'. Cognates across European languages, such as German Acetyl and French acétyle, reflect the shared international vocabulary of chemistry.
Related word forms
How acetyl is actually used
Strictly a technical term used in chemistry and biochemistry; it rarely appears outside scientific writing. In speech it is usually pronounced with stress on the first syllable, though some chemists place stress on the second syllable (/əˈsiːtɪl/).
Easily confused with acetyl
Acetic describes acetic acid itself (the acid in vinegar), while acetyl refers to the CH₃CO– fragment derived from that acid.
An acetal is a class of compounds formed from aldehydes and alcohols, whereas acetyl names a specific chemical group; the two look similar in spelling but are unrelated terms.