| a device for performing mathematical calculations, consisting essentially of a ruler having a sliding piece moving along it, both marked with graduated, usually logarithmic, scales: now largely replaced by the electronic calculator. |
| slide rule n. A device consisting of two logarithmically scaled rules mounted to slide along each other so that multiplication, division, and other more complex computations are reduced to the mechanical equivalent of addition or subtraction. |
slide rule
a device consisting of graduated scales capable of relative movement, by means of which simple calculations may be carried out mechanically. Typical slide rules contain scales for multiplying, dividing, and extracting square roots, and some also contain scales for calculating trigonometric functions and logarithms. The slide rule remained an essential tool in science and engineering and was widely used in business and industry until it was superseded by the portable electronic calculator late in the 20th century.
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