annulus

noun

an·nu·lus | \ ˈan-yə-ləs

plural annuli\-ˌlī,

-(ˌ)lē \ also annuluses

Definition of annulus

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

Examples of annulus in a Sentence

Recent Examples on the Web

They are easily identified by the red-brown cap fading to tan, white to lilac-gray gills, firm texture, and annulus (ring) around the stout stipe (stalk). — Sunset, "How to Grow Mushrooms," 22 Jan. 2018 Our last partial eclipse was Oct 23, 2014; the biggest one in recent memory is the May 10, 1994 annular eclipse (annular as in annulus = ring). — Dawn Mitchell, Indianapolis Star, "Retro Eclipse: When day turned to night and back again," 18 Aug. 2017 Instead, for a few minutes the sun looks like a striking annulus, or ring, which is why an annular eclipse is also often called a ring of fire. — Andrew Fazekas, National Geographic, "‘Ring of Fire’ Solar Eclipse This Week: How to See It," 31 Aug. 2016

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'annulus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.