What does coaxial mean?
Coaxial is a technical adjective describing two or more objects—typically cylinders, discs, shafts, or cables—that share the same central axis, rotating or lying along one common straight line. The word appears most often in engineering and physics contexts: coaxial cables sandwich an inner conductor and an outer shielding layer around a single axis, which is precisely what lets them carry radio-frequency signals like television and internet feeds with minimal interference. Helicopters with coaxial rotors stack two sets of blades on one mast spinning in opposite directions. Beyond hardware, the term also appears in geometry for concentric figures sharing an axis of symmetry. Coaxial carries a precise, professional register and is essentially confined to technical writing and speech, though its shortened form "coax" has entered everyday vocabulary thanks to the ubiquity of coaxial cabling. Its opposite concept is eccentricity—being off-axis.
adjectiveHaving a common axis; rotating about or situated on the same central line, especially of two or more cylinders, circles, or shafts.
- Geometry and engineering: having two or more surfaces, circles, or shafts arranged around one shared straight axis (e.g. coaxial cylinders).
- Electronics: describing cable construction in which an inner conductor runs along the same axis inside an outer cylindrical shield (coaxial cable).
"The two lenses were mounted on a coaxial mount to keep their optical axes perfectly aligned."
"The helicopter's coaxial rotors turn in opposite directions on a single mast."
"Connect the modem to the wall outlet using a coaxial cable."
That chunky screw-on cable linking your TV to the wall has carried television signals into homes for decades — and it's named for the clever fact that its inner wire and outer shield spin around exactly the same invisible axis.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of coaxial
Coaxial was formed in the nineteenth century from the Latin-derived prefix co-, meaning "together," combined with "axial," from Latin axis meaning a pivot or axle line. It literally means "sharing an axis." It belongs to a family including axis, axial, and related scientific terms built on the same Latin root. The word gained wide currency with the development of coaxial cable technology in the early twentieth century.
Related word forms
How coaxial is actually used
A technical term used mainly in physics, engineering, geometry, and electronics; rare in everyday conversation except through the familiar phrase "coaxial cable." Neutral in connotation and identical in British and US English.
Easily confused with coaxial
"Coax" is an informal shortening of "coaxial cable" (or a verb meaning to gently persuade), while "coaxial" is the full adjective describing objects that share an axis.