any circular or rotating mechanism; "the machine punched out metal circles"
a curved section or tier of seats in a hall or theater or opera house; usually the first tier above the orchestra; "they had excellent seats in the dress circle"
ellipse in which the two axes are of equal length; a plane curve generated by one point moving at a constant distance from a fixed point; "he calculated the circumference of the circle"
something approximating the shape of a circle; "the chairs were arranged in a circle"
(psychology) the aggregate of the responses or reactions or movements made by an organism in any situation
the action or reaction of something (as a machine or substance) under specified circumstances; "the behavior of small particles can be studied in experiments"