A plane curve everywhere equidistant from a given fixed point, the center. A planar region bounded by a circle. Something, such as a ring, shaped like such a plane curve. A circular course, circuit, or orbit: a satellite's circle around the earth. A traffic circle. A curved section or tier of seats in a theater. A series or process that finishes at its starting point or continuously repeats itself; a cycle. A group of people sharing an interest, activity, or achievement: well-known in artistic circles. A territorial or administrative division, especially of a province, in some European countries. A sphere of influence or interest; domain. Logic A vicious circle. To make or form a circle around; enclose. See Synonyms at surround. To move in a circle around. To move in a circle. See Synonyms at turn. circle the wagons To take a defensive position; become defensive.