plural abaci ˈa-bə-ˌsī How to pronounce abacus (audio)
ə-ˈba-ˌkī How to pronounce abacus (audio)
or abacuses
: an instrument for performing calculations by sliding counters along rods or in grooves
: a slab that forms the uppermost member or division of the capital of a column

Illustration of abacus

Illustration of abacus
  • abacus 1

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Probably of Babylonian origin, an abacus is a calculating instrument that uses beads that slide along a series of wires or rods set in a frame to represent the decimal places. It is the ancestor of the modern digital calculator. Used by merchants in the Middle Ages throughout Europe and the Arabic world, it was gradually replaced by arithmetic based on Hindu-Arabic numerals. Though rarely used in Europe past the 18th century, it is still used in the Middle East, China, and Japan.

Word History


Latin, from Greek abak-, abax, literally, slab

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of abacus was in the 14th century

Dictionary Entries Near abacus

Cite this Entry

“Abacus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/abacus. Accessed 2 Dec. 2022.

Kids Definition



plural abaci ˈab-ə-sī How to pronounce abacus (audio) -ˌkē How to pronounce abacus (audio)
or abacuses
: an instrument for making calculations by sliding counters along rods or in grooves

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