doughnut vs annulus

doughnut and annulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
doughnut	Yes	No	No	No
annulus	Yes	No	No	No

As nouns, doughnut and annulus are synonyms defined as:

Other synonyms of doughnut include anchor ring, halo, ring.

doughnut (noun)	annulus (noun)
a small ring-shaped friedcake	(Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
a toroidal shape	a toroidal shape