Definition of annulus
plural annuli
play
\-ˌlī, -(ˌ)lē\
also annuluses
1
:ring
2
:a part, structure, or marking resembling a ring: such as
a
:a line of cells around a fern sporangium that ruptures the sporangium by contracting
b
:a growth ring (as on the scale of a fish) that is used in estimating age
