Abacus definition

ăbə-kəs, ə-băkəs
A manual computing device consisting of a frame holding parallel rods strung with movable counters.
noun
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5
(archit.) A slab forming the uppermost part of the capital of a column.
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A frame with beads or balls that can be slid on wires or in slots, for doing or teaching arithmetic.
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(architecture) A slab on the top of the capital of a column.
noun
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A calculating table or frame; an instrument for performing arithmetical calculations by balls sliding on wires, or counters in grooves, the lowest line representing units, the second line, tens, etc. [First attested in the late 17th century.]

I've heard merchants still use an abacus for adding things up in China.

noun
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The definition of an abacus is a simple device you can use to make manual mathematical calculations by sliding counters along rows of wires set inside a frame.

An example of an abacus is a child’s bead counting toy.

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(architecture) The uppermost portion of the capital of a column, immediately under the architrave. [First attested in the mid 16th century.]
noun
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A board, tray, or table, divided into perforated compartments, for holding cups, bottles, or the like; a kind of cupboard, buffet, or sideboard. [First attested in the late 18th century.]
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Other Word Forms

Noun

Singular:
abacus
Plural:
abaci, abacuses

Origin of abacus

  • Middle English from Latin from Greek abax abak- counting board perhaps from a Semitic source akin to Hebrew ’ābāq dust ℵbq in Semitic roots

    From American Heritage Dictionary of the English Language, 5th Edition

  • From Latin abacus, abax; from Ancient Greek ἄβαξ (abaks, “board covered with sand”), possibly from Hebrew אבק (āvāq, “dust”).

    From Wiktionary