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plural aux [oh] /oʊ/. French.
  1. to the; at the; with the.
Compare à la.


  1. author.Also au
  2. Symbol, Chemistry. gold.

Origin of Au

From the Latin word aurum


  1. astronomical unit.


or a.u.

  1. angstrom unit.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for au

Contemporary Examples

Historical Examples

  • She is going to the coast for the season, and I called to-night to say au revoir.

  • “‘Say au revoir, but not good-by,’” sang Miss Sherborne sentimentally.

    Cap'n Warren's Wards

    Joseph C. Lincoln

  • "Well, au revoir," he cried in a strained voice, and then fled down the stairs.

    The Christian

    Hall Caine

  • "Au rvoir, M. de Luynes," he said significantly as he got into the saddle.

    The Suitors of Yvonne

    Raphael Sabatini

  • Malhereux au jeux, heureux en amour, as we used to say formerly.

    Jack Hinton

    Charles James Lever

British Dictionary definitions for au


the internet domain name for
  1. Australia


the chemical symbol for
  1. gold

Word Origin

from New Latin aurum


abbreviation for
  1. African Union
  2. Also: a.u. angstrom unit
  3. Also: a.u. astronomical unit
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 au


chemical symbol for "gold," from Latin aurum "gold" (see aureate).

French, "at the, to the," from Old French al, contraction of a le, with -l- softened to -u-, as also poudre from pulverem, chaud from calidus, etc. Used in many expressions in cookery, etc., which have crossed the Channel since 18c., e.g. au contraire, literally "on the contrary;" au gratin, literally "with scrapings;" au jus, literally "with the juice."

Online Etymology Dictionary, © 2010 Douglas Harper

au in Medicine


  1. The symbol for the elementgold


  1. auris utraque (each ear)

au in Science


  1. The symbol for gold.


  1. Abbreviation of astronomical unit


  1. A soft, shiny, yellow element that is the most malleable of all the metals. It occurs in veins and in alluvial deposits. Because it is very durable, resistant to corrosion, and a good conductor of heat and electricity, gold is used as a plated coating on electrical and mechanical components. It is also an international monetary standard and is used in jewelry and for decoration. Atomic number 79; atomic weight 196.967; melting point 1,063.0°C; boiling point 2,966.0°C; specific gravity 19.32; valence 1, 3. See Periodic Table. See Note at element.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.