"What's the plural of abacus?"

The plural of abacus is abaci or abacuses.

Definition of abacus:

The abacus is an ancient counting device that has been used for centuries in different parts of the world. It consists of a frame with wires or rods on which beads or counters are placed to represent numbers.

Which is correct: Abacuses or Abaci?

The word abacus comes from the Greek word "abax," which means "board" or "slab." Being of Greek origin, the Greek pluralization of the word “abacus” is “abaci”.  This follows the same rules as many similar words ending in -us such as cactus, radius and platypus.

However, over time, the word has evolved, and the anglicized plural form "abacuses" has slowly grown in usage.

See the graph at the bottom of the page for a comparison of the instances of each word in written English over time.

Is Abacus a Countable or Uncountable Noun?

Abacus is a countable noun, which means it refers to a specific object that can be counted.

In English grammar, nouns can be categorized as either countable or uncountable. Countable nouns are things that can be counted, such as "book," "apple," or "chair," while uncountable nouns are things that cannot be counted, such as "water," "sugar," or "furniture."

For example, if you have two abacuses, you can say, "I have two abacuses," because "abacus" is a countable noun. In contrast, you cannot say, "I have two sugars," as "sugar" is an uncountable noun. Instead, you can say, "I have two packets of sugar," or "I have two spoonfuls of sugar."


In conclusion, the plural of abacus can be either "abaci" or "abacuses," and both are grammatically correct. The choice between the two forms depends on the context and personal preference.

Regardless of the plural form used, the abacus remains an important tool for teaching and learning mathematics, as well as for providing a fascinating insight into the history of human innovation.

Plural of Abacus Example Sentences

Example sentences of the singular and plural forms of the word abacus:


  • The abacus is a useful tool for teaching children basic mathematics.
  • She was fascinated by the intricacy of the abacus, and how quickly it could solve problems.
  • I used an abacus to calculate the total cost of my shopping.


  • The abacuses were lined up neatly on the table, ready for the students to use.
  • He collected abacuses from different countries and displayed them in his museum.
  • The abacuses that were used in ancient China were quite different from those used in Europe.

Abacuses vs. abaci

The graph shows the occurances of the plural of abacus in written English since 1800 using Google's Ngram Viewer.



Similar Questions

What's the plural of...

The plural of abacus is abaci or abacuses
The plural of abacus is abaci or abacuses