aba·​cus | \ ˈa-bə-kəs How to pronounce abacus (audio) , ə-ˈba- How to pronounce abacus (audio) \
plural abaci\ ˈa-​bə-​ˌsī How to pronounce abacus (audio) , -​ˌkē ; ə-​ˈba-​ˌkī How to pronounce abacus (audio) \ or abacuses

Definition of abacus

1 : an instrument for performing calculations by sliding counters along rods or in grooves
2 : 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.

First Known Use of abacus

14th century, in the meaning defined at sense 1

History and Etymology for abacus

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

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

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Cite this Entry

“Abacus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/abacus. Accessed 20 Sep. 2021.

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English Language Learners Definition of abacus

: a device used for counting and calculating by sliding small balls or beads along rods or in grooves


aba·​cus | \ ˈa-bə-kəs How to pronounce abacus (audio) \
plural abaci\ ˈa-​bə-​ˌsī \ or abacuses

Kids Definition of abacus

: an instrument for doing arithmetic by sliding counters along rods or in grooves

More from Merriam-Webster on abacus

Nglish: Translation of abacus for Spanish Speakers

Britannica English: Translation of abacus for Arabic Speakers

Britannica.com: Encyclopedia article about abacus


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