1
- a part of a curve, especially a part of the circumference of a circle弧。
1.1
- a shape resembling this or something with such a shape弧状物体：
the huge arc of the sky.
茫茫苍穹。
1.2
- a curving trajectory弧形射体轨道：
he swung his torch in a wide arc*
他把手电筒拉着大圈子左右挥动。
1.3
- as modifier Mathematics indicating the inverse of a trigonometrical function【数】反三角函数
- ORIGIN: from the former method of defining trigonometrical functions by arcs.
2
- a luminous electrical discharge between two electrodes or other points电弧。
3
- (in a novel, play, or film) the development or resolution of the narrative or principal theme（小说、戏剧或电影） 情节（或主题）的发展（或结局）：
his transformation provides the emotional arc of the story.
他的转变为故事提供了情感发展轨迹。
(arced, arcing)no obj.
1
- with adverbial of direction move with a curving trajectory循弧线运动：
the ball arced across the room.
球以弧形路线飞过房间。
2
- usu. as noun arcing form an electric arc形成电弧：
check that switches operate properly with no sign of arcing.
检查一下开关是否使用正常, 是否不带电弧。
短语
minute of arc
- 见
MINUTE 1 （义项2）。
second of arc
- 见
SECOND2 （义项2）。
词源
late Middle English （denoting the path of a celestial object， especially the sun， from horizon to horizon）： via Old French from Latin arcus 'bow， curve'.