Plural of annulus; multiple ring-shaped objects or the areas between concentric circles.
From Latin 'annulus' (ring) plus English plural suffix '-es.' The Latin plural 'annuli' is also used, especially in technical contexts.
In geometry, you can have 'annuli' (fancy Latin) or 'annuluses' (English way)—both are correct, but English speakers usually pick whichever sounds less pretentious in context.
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