noun, plural ab·a·cus·es, ab·a·ci [ab-uh-sahy, -kahy, uh-bak-ahy] /ˈæb əˌsaɪ, -ˌkaɪ, əˈbæk aɪ/.
Origin of abacus
Examples from the Web for abaci
The capitals are similarly carved, and the abaci have conventional foliage.
The capitals here are very close imitations of Classical work, with the abaci frequently concave on plan.Brick and Marble in the Middle Ages|George Edmund Street
Take, for instance, this story of the Cat and the Rats, which I sketched on one of the abaci of the southern walk of the cloister.
It has three shafts on each side, all with good capitals and abaci, from which spring two carved and one plain arch.Portuguese Architecture|Walter Crum Watson
The abaci are carved throughout with conventional foliage, well arranged and delicately cut.