circle (ˈsɜːk^{ə}l)  
—n  
1.  maths a closed plane curve every point of which is equidistant from a given fixed point, the centre. Equation: (x h)² + (y k)² = r² where r is the radius and (h, k) are the coordinates of the centre; area πr²; circumference: 2πr 
2.  the figure enclosed by such a curve 
3.  theatre the section of seats above the main level of the auditorium, usually comprising the dress circle and the upper circle 
4.  something formed or arranged in the shape of a circle 
5.  a group of people sharing an interest, activity, upbringing, etc; set: golf circles; a family circle 
6.  a domain or area of activity, interest, or influence 
7.  a circuit 
8.  a process or chain of events or parts that forms a connected whole; cycle 
9.  great circle See also small circle a parallel of latitude 
10.  the ring of a circus 
11.  one of a number of Neolithic or Bronze Age rings of standing stones, such as Stonehenge, found in Europe and thought to be associated with some form of ritual or astronomical measurement 
12.  hockey See striking circle 
13.  See vicious circle a circular argument 
14.  come full circle See also vicious circle to arrive back at one's starting point 
15.  go round in circles, run round in circles to engage in energetic but fruitless activity 
—vb  
16.  to move in a circle (around): we circled the city by car 
17.  (tr) to enclose in a circle; encircle 
[C14: from Latin circulus a circular figure, from circus ring, circle]  
'circler  
—n 
circle cir·cle (sûr'kəl)
n.
A ringshaped structure or group of structures.
A line or process with every point equidistant from the center.
circle (sûr'kəl) Pronunciation Key
(click for larger image in new window) A closed curve whose points are all on the same plane and at the same distance from a fixed point (the center). 
circling (the drain) definition
