American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "abaci" in a sentence
"Alas, abaci have already been commoditized --you can own your own franchise!"
"Studies have shown that kids who master abaci have a better comprehension of math."
"Digital calculators notwithstanding, some abaci can still be found in a grade school classroom or two."