Main Entry: an·nu·lus

Pronunciation: \ˈan-yə-ləs\

Function: noun

Inflected Form(s): plural an·nu·li \-ˌlī, -(ˌ)lē\ also an·nu·lus·es

Etymology: Medieval Latin, from Latin anulus finger ring, from anus ring — more at anus

Date: 1563

1 : ring
2 : a part, structure, or marking resembling a ring: 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