a. 环形的

[医] 环状的

[ adj ]
shaped like a ring
<adj.all>

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.

2. Banded or marked with circles.

{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.