The Collaborative International Dictionary of English v.0.48:

Annular \An"nu*lar\, a. [L. annularis, fr. annulis ring: cf. F.
   annulaire.]
   1. Pertaining to, or having the form of, a ring; forming a
      ring; ringed; ring-shaped; as, annular fibers.
      [1913 Webster]

   2. Banded or marked with circles.
      [1913 Webster]

   Annular eclipse (Astron.), an eclipse of the sun in which
      the moon at the middle of the eclipse conceals the central
      part of the sun's disk, leaving a complete ring of light
      around the border.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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