Abaci

Part of speech: noun

Pronunciation: /ˈæbəkaɪ/

Definitions

1. A type of calculating device consisting of a frame with rods and sliding beads used for arithmetic tasks
2. A traditional tool for calculation employed in various cultures, characterized by a series of beads that can be moved along bars
3. A manual method of computation using a structured arrangement of beads found on a frame, commonly used before modern calculators

Etymology: "Abaci" is the plural of "abacus," so it names more than one counting frame at a time. The singular goes back to Latin "abacus," which in turn came from Greek "abax," a word for a flat board or slab, often one covered with sand or dust for drawing or calculating. That origin explains the shape of the thing: an early counting tool was little more than a smooth surface on which marks or pebbles could be moved about. The plural comes straight from Latin "abacī," the regular Latin plural of "abacus." English kept that Latin ending rather than adding an English "-es," which is why the form looks unusual to many readers. Its pronunciation, with the stress on the first syllable, follows the same pattern as the singular.