The Collaborative International Dictionary of English v.0.48:

Circinate \Cir"ci*nate\, a. [L. circinatus, p. p. of circinare
   to make round, fr. circinus a pair of compasses, from Gr. ? a
   circle.] (Bot.)
   Rolled together downward, the tip occupying the center; -- a
   term used in reference to foliation or leafing, as in ferns.
   --Gray.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Circinate \Cir"ci*nate\, v. t.
   To make a circle around; to encompass. [Obs.] --Bailey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

circinate
    adj 1: shaped like a ring [syn: annular, annulate,
           annulated, circinate, ringed, ring-shaped,
           doughnut-shaped]