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See more synonyms for au on Thesaurus.com
plural aux [oh] /oʊ/. French.
  1. to the; at the; with the.
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Compare à la.


  1. author.Also au
  2. Symbol, Chemistry. gold.
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Origin of Au

From the Latin word aurum



or a.u.

  1. angstrom unit.
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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
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the chemical symbol for
  1. gold
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Word Origin

from New Latin aurum


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

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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."

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Online Etymology Dictionary, © 2010 Douglas Harper

au in Medicine


  1. The symbol for the elementgold


au in Science




The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.