abacus
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1 calculating tool (n.) B2 Upper Intermediate Matha frame with beads sliding on wires, used for counting and math.
a manual calculating device consisting of a frame with beads or counters sliding on rods.
ExampleThe children learned how to add large numbers using a wooden abacus.
ExampleBefore the widespread adoption of electronic calculators, the abacus remained a primary tool for rapid arithmetic in many merchant cultures.
UsageThe plural form is usually 'abacuses', though 'abaci' is occasionally found in technical or older texts.
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2 part of a column (n.) C2 Proficiency Technical Architecturethe flat slab at the very top of a column that supports the weight above it.
the uppermost portion of a column capital, serving as a transition between the column and the architrave.
ExampleThe architect pointed to the square abacus resting on top of the decorated column.
ExampleIn the Doric order, the abacus is a simple square slab, whereas in later styles it often features more elaborate moulding and decoration.
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3 ancient counting board (n.) C2 Proficiency Archaic Technicalan old type of table covered in sand used for drawing or math.
a historical table or tray scattered with sand, used in antiquity for performing calculations or geometric drawings.
ExampleThe scholar studied how ancient Greeks used a sand abacus for geometry.
ExampleArchaeological evidence suggests that the sand-covered abacus preceded the more familiar bead-and-rod frame as a tool for complex computation.
From Late Middle English abacus, abagus, agabus (“abacus; art of counting with an abacus”), from Latin abacus, abax (“sideboard or table with a slab at the top; slab at the top of a column; counting board, sand table; board for playing games”) (compare Late Latin abacus (“art of arithmetic”)), from Ancient Greek ἄβαξ (ábax, “slab, counting board; board covered with sand for drawing; plate; dice-board”). Doublet of abaque. The plural form abaci is reinforced from Latin abacī.