# abacus

/ˈæbəkəs/ (US) · /ˈæbækəs/ (UK)

Source: https://englishreference.com/word/abacus
Updated: 2026-05-01

## Senses

### 1. calculating tool

noun · CEFR B2

a frame with beads sliding on wires, used for counting and math.

For teachers: a manual calculating device consisting of a frame with beads or counters sliding on rods.

- The children learned how to add large numbers using a wooden abacus.
- Before the widespread adoption of electronic calculators, the abacus remained a primary tool for rapid arithmetic in many merchant cultures.

Usage: The plural form is usually 'abacuses', though 'abaci' is occasionally found in technical or older texts.

### 2. part of a column

noun · CEFR C2 · Technical

the flat slab at the very top of a column that supports the weight above it.

For teachers: the uppermost portion of a column capital, serving as a transition between the column and the architrave.

- The architect pointed to the square abacus resting on top of the decorated column.
- In the Doric order, the abacus is a simple square slab, whereas in later styles it often features more elaborate moulding and decoration.

### 3. ancient counting board

noun · CEFR C2 · Archaic · Technical

an old type of table covered in sand used for drawing or math.

For teachers: a historical table or tray scattered with sand, used in antiquity for performing calculations or geometric drawings.

- The scholar studied how ancient Greeks used a sand abacus for geometry.
- Archaeological evidence suggests that the sand-covered abacus preceded the more familiar bead-and-rod frame as a tool for complex computation.

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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.