abacuses

noun pl. abacuses ab′a·cuses or abaci ab′a·ci′ (-sī′)

1. a frame with beads or balls that can be slid on wires or in slots, for doing or teaching arithmetic
2. Archit. a slab forming the uppermost part of the capital of a column

Etymology: L < Gr abax (gen. abakos), counting board, slab