What does acyclic mean?
Acyclic is an adjective meaning 'not cyclic' — that is, lacking cycles or closed loops. It is chiefly a technical term with two main domains of use. In chemistry, an acyclic compound is one whose atoms are joined in open chains rather than rings; simple alkanes such as propane and butane are classic examples. In mathematics and computer science, an acyclic graph contains no path that starts and ends at the same vertex, a property essential to structures like directed acyclic graphs (DAGs), which underpin everything from build systems to version control and data pipelines. The word carries no emotional connotation — it is neutral, precise, and formal, appearing in textbooks, research papers, and technical documentation rather than casual conversation. Its opposite, cyclic, is equally common in these fields, and the contrast between the two terms is often central to explaining why certain systems behave predictably while others loop indefinitely.
adjectiveNot cyclic; having no cycles. In chemistry, describing a compound whose atoms do not form a ring; in mathematics and computing, describing a graph or structure that contains no closed loops.
- Of a chemical compound: having an open-chain molecular structure, not containing any rings of atoms.
- Of a graph or mathematical structure: containing no cycles or closed paths.
"The dependency graph must remain acyclic, or the build process will loop forever."
"Alkanes are acyclic hydrocarbons, their carbon atoms arranged in open chains rather than rings."
"A directed acyclic graph is ideal for representing task dependencies because no task can depend on itself, directly or indirectly."
Every time your software builds without freezing, it's because the computer checked that its dependencies form an acyclic graph — no loops allowed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acyclic
Acyclic derives from the Greek noun kyklos, meaning 'circle' or 'wheel', which entered English via Latin as cycle. The prefix a- comes from Greek, where it functions as a negative ('not', 'without'), so acyclic literally means 'without circles'. The word was formed on the model of earlier scientific compounds using the same prefix, and it emerged alongside related terms such as monocyclic and polycyclic as chemists and mathematicians needed precise vocabulary for ring versus non-ring structures.
How acyclic is actually used
Acyclic is a technical term used almost exclusively in chemistry, mathematics, and computer science; it is rare in everyday speech. It is typically used attributively before a noun (an acyclic compound, an acyclic graph).
Easily confused with acyclic
Cyclic describes structures containing one or more rings or closed loops, while acyclic describes structures with none.