circle (ser'kl). 1

A continuous curved line in the shape of a ring, every point of which is equidistant from a common center. For mathematical purposes, a c. is supposed to be divided into 360 equal parts (degrees). 2. Any curved line, structure, or appliance more or le resembling a c. (1st def.). 3. A series of similar or related objects, events, etc., so connected as to maintain a common action or produce a common result. 4. See circuit. c. of sensation, c. of sensibility. A circular or oval area of the skin within the limits of which two tactile impre ions are referred to the same point. C of Will is. A roughly circular channel of communication between the arteries of the base of the brain, formed by the anterior, middle, and posterior cerebral and the anterior and posterior communicating arteries, color c. An instrument for testing color blindne adapted to Holmgren's method, diffusion c. See under diffusion, dispersion c. See under dispersion, galvanic c. A galvanic circuit, polar c. A more or le decided circular groove on the surface of a cell during karyokinesis, indicating the termination of the striae of the antipodal cone, voltaic c. A galvanic circuit. [B. N. A., circulus.] [Gr., kirkos, kyklos, circle.]