What does arc mean?
An arc is a curved section of a line or circle — geometrically, the portion of a curve lying between two of its points. Beyond mathematics, the word describes any smooth, sweeping curved path: the flight of a thrown ball, the swing of a pendulum, or the glowing span of a rainbow all move in arcs. In modern usage, arc has also taken on a rich figurative life, particularly in storytelling, where a 'character arc' or 'story arc' describes how a person or plot develops from beginning to end. The word carries no strong emotional connotation; it is precise, visual, and versatile, equally at home in a geometry textbook, a sports commentary, and a screenwriting manual. Derived from the Latin 'arcus', meaning bow or arch, it shares ancestry with words like 'arch', 'arcade', and 'archer', linking the humble curve to some of architecture's most enduring forms.
A part of a curve, especially the continuous portion of a circle between two points; more broadly, a smooth curving path or trajectory.
"The comet described a long arc across the evening sky."
In geometry, an arc is typically measured in degrees or radians along the circumference of a circle.
Figuratively, the overall shape or progression of a narrative, character development, or sequence of events over time.
"Critics praised the film for giving even minor characters a satisfying arc."
This sense is common in film, television, and literary criticism, where 'character arc' and 'story arc' are standard vocabulary.
The standard plural of arc is 'arcs', used when referring to multiple curved segments or paths.
"The diagram showed three intersecting arcs forming the design."
The same Latin word that gave us 'arc' gave us 'arch' and 'arcade' — every rainbow you've ever seen is technically an arc of light refracted through raindrops.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of arc
Arc comes from the Latin 'arcus', meaning 'bow' or 'arch', which itself derives from the Proto-Indo-European root *arkw-, associated with bending or curving. The word entered English in the late Middle Ages via Old French 'arc', initially referring to the weapon (the bow) before its geometric sense became established. Its cognates include 'arch', 'arcade', 'archer', and 'archive', all tracing back to the same Latin root.
How arc is actually used
Arc is neutral in register and appears in both technical contexts (geometry, physics, engineering) and everyday ones. In recent decades it has become especially common in figurative use for storytelling — 'character arc' and 'story arc' are standard terms in film, television, and literary criticism. The plural is 'arcs'.
Easily confused with arc
An arch is a curved structure spanning an opening that supports weight above it, while an arc is simply any curved segment of a line or path.
An ark is a chest or boat (as in Noah's ark or the Ark of the Covenant), whereas an arc is a curved shape or path.