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[al-gol, -gawl]
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  1. a star of the second magnitude in the constellation Perseus: the first known and most famous eclipsing binary star.

Origin of Algol

1350–1400; Middle English < Arabic, equivalent to al the + ghūl ghoul; as translation of Greek (Ptolemy) gorgónion the head of the Gorgon Medusa, held by Perseus
Also called Demon Star.


[al-gol, -gawl]
  1. a computer language in which information is expressed in algebraic notation and according to the rules of Boolean algebra.

Origin of ALGOL

1955–60; algo(rithmic) l(anguage)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for algol

Historical Examples

  • Every third night Algol has its light reduced for several hours.

    The Outline of Science, Vol. 1 (of 4)

    J. Arthur Thomson

  • Algenib and Algol form with γ Andromedæ, a right-angled triangle.

    A Field Book of the Stars

    William Tyler Olcott

  • The most easterly one is β Persei, known as Algol, the famous variable.

    A Field Book of the Stars

    William Tyler Olcott

  • Mention has been made of a slight irregularity in Algol's period of variation.

  • It is to the second of these types that Algol is supposed to belong.

    Astronomy of To-day

    Cecil G. Dolmage

British Dictionary definitions for algol


  1. the second brightest star in Perseus, the first known eclipsing binary. Visual magnitude: 2.2–3.5; period: 68.8 hours; spectral type (brighter component): B8V

Word Origin

C14: from Arabic al ghūl the ghoul


  1. a computer programming language designed for mathematical and scientific purposes; a high-level language

Word Origin

C20 alg (orithmic) o (riented) l (anguage)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for algol


Beta Persei, variable star in the constellation Perseus, late 14c., literally "the Demon," from Arabic al-ghul "the demon" (see ghoul). It corresponds, in modern representations of the constellation, to the gorgon's head Perseus is holding, but it probably was so called because it visibly varies in brightness every three days, which sets it apart from other bright stars. The computer language (1959) is a contraction of algo(rithmic) l(anguage); see algorithm.

Online Etymology Dictionary, © 2010 Douglas Harper