Main Entry: aba·cus

Pronunciation: \ˈa-bə-kəs, ə-ˈba-\

Function: noun

Inflected Form(s): plural aba·ci \ˈa-bə-ˌsī, -ˌkē; ə-ˈba-ˌkī\ or aba·cus·es

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

Date: 14th century

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

[abacus illustration]