What does coil mean?
A coil is a length of material — rope, wire, hair, tubing — wound into a connected series of rings or a spiral. The word works both as a noun, naming the wound object itself ('a coil of cable'), and as a verb describing the act of winding ('to coil a hose'). Each individual ring within the spiral is also called a coil, as in 'a spring with twenty coils'. In engineering, a coil refers specifically to a conductor wound in loops that acts as an inductor, found in transformers, motors, and ignition systems. Figuratively and descriptively, 'coil' conveys a compact, spring-like energy: snakes coil before striking, smoke coils upward, and tension coils in a scene. Derived forms include 'coiled' and 'coiling'. The word entered English in the early seventeenth century, likely from Old French 'coillir' meaning 'to gather', ultimately tracing back to Latin 'colligere' — the same root behind 'collect'. Its enduring usefulness lies in capturing both a physical shape and the latent force that shape implies.
A length of rope, wire, hair, or similar material wound into a connected series of rings; a single ring or turn of such a series; or, in electrical engineering, a conductor wound into a spiral that functions as an inductor.
"The mechanic replaced the faulty ignition coil."
In technical contexts, 'coil' almost always refers to an electrical inductor or a heating/cooling element (e.g., in an HVAC system).
To wind something into a series of rings or a spiral; or (of a person, animal, or thing) to move with a twisting, spring-like motion, often in preparation for action.
"The cat coiled itself on the windowsill and fell asleep."
Often used with 'itself' when describing animals or people settling into position, or with 'up' when storing flexible material.
Regular plural. Used both for multiple separate wound objects ('several coils of wire') and for the individual turns within one winding ('the spring has twelve coils').
"The transformer contains several copper coils wrapped around an iron core."
The word 'coil' may trace back to the Latin 'colligere' — 'to gather together' — the same root that gives us 'collect', so every time you coil a rope you are literally gathering it together.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of coil
The word 'coil' first appeared in English in the early seventeenth century, borrowed from Old French 'coillir' (modern French 'cueillir'), meaning 'to gather, pick, or collect'. This derives from the Latin verb 'colligere', formed from 'com-' ('together') and 'legere' ('to gather'), which also gives English 'collect' and 'college'. The original sense of gathering up loose material naturally evolved into the specific idea of winding it into rings.
Related word forms
How coil is actually used
Common in both everyday and technical registers; the verb sense often appears reflexively or with 'up' (coil up). The electrical sense is standard in physics and engineering contexts.
Easily confused with coil
The electrical sense — an inductor wound from wire — is a specialized technical use of the same word, not a different word.