The Collaborative International Dictionary of English v.0.48:
Circularity \Cir`cu*lar"i*ty\, n. [LL. circularitas.] The quality or state of being circular; a circular form. [1913 Webster]WordNet (r) 3.0 (2006):
circularity n 1: the roundness of a 2-dimensional figure [syn: circularity, disk shape]