[′sər·kyə·ləs] (biology) Any of various ringlike structures, such as the vascular circle of Willis or the concentric ridges on fish scales.
circulus
cir·cu·lus
, gen. and pl.
cir·cu·li
(ser'kyū-lŭs, -lī), [TA] 2. A circle formed by connecting arteries, veins, or nerves. [L. dim. of circus, circle]
cir·cu·lus
, gen. and pl. circuli (sĭr'kū-lŭs, -lī) [TA] 1. Synonym(s): circle (1) . 2. A circle formed by connecting arteries, veins, or nerves. [L. dim. of circus, circle]