arc

noun

• 1a part of a curve, especially a part of the circumference of a circle: the point where a tangential line touches the arc of a circle
• a shape or structure resembling an arc:the huge arc of the sky
• a curving trajectory:he swung his torch in a wide arc
• [as modifier] Mathematics indicating the inverse of a trigonometrical function.

  [from the former method of defining trigonometrical functions by arcs]

• 2a luminous electrical discharge between two electrodes or other points: modern welding generators are designed so that there is a high voltage for striking the arc

• 3(in a novel, play, or film) the development or resolution of the narrative or principal theme:his transformation provides the emotional arc of the story

verb (arcs, arcing /ˈɑːkɪŋ/, arced /ɑːkt/)

• 1 [with adverbial of direction] move with a curving trajectory:the ball arced across the room

• 2 (usually as noun arcing) form an electric arc:check that switches operate properly with no sign of arcing