What does annular mean?
The definition of annular
An”nu*lar, a.
Etym: [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.