# abaci

CEFR C2 · Noun

Source: https://englishreference.com/word/abaci
Updated: 2026-05-02

## Definition

the plural form of abacus. These are old tools with beads on wires that people use for counting and math.

For teachers: the plural form of abacus, referring to manual calculating devices consisting of beads or stones moved along rods or grooves. This Latinate plural is less common in modern usage than the regularised 'abacuses'.

## Examples

- The students practiced their math skills using wooden abaci.
- The museum display featured several ancient abaci used by merchants across different centuries and cultures.
- While digital calculators have rendered manual tools obsolete in most classrooms, some traditional schools still teach the manipulation of abaci to help children visualize the base-ten number system.

## Pitfalls

- Not "one abaci" but "one abacus" — 'Abaci' is the plural form; the singular form is 'abacus'.

## Usage notes

- The plural form of 'abacus'. While 'abaci' follows Latin morphology, 'abacuses' is more frequent in contemporary English.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.