• synonyms


or a'a

  1. basaltic lava having a rough surface.
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Compare pahoehoe.

Origin of aa

First recorded in 1855–60, aa is from the Hawaiian word ʿaʿā



  1. a proportional shoe width size, narrower than A and wider than AAA.
  2. the smallest proportional brassiere cup size.
  3. a quality rating for a corporate or municipal bond, lower than AAA and higher than A.
  4. Electricity. a battery size for 1.5 volt dry cells: diameter, 0.6 inches (1.4 cm); length, 2 inches (5 cm).
  5. British. a designation for motion pictures certified as unsuitable for children under 14 unless accompanied by an adult.Compare A(def 11), U(def 6), X(def 9).
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or āa

  1. (in prescriptions) ana2.
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Origin of a̅a̅

From the Greek word aná, with superscript bar representing the nasal consonant


or aa


  1. Alcoholics Anonymous.
  2. antiaircraft.
  3. antiaircraft artillery.
  4. Associate in Accounting.
  5. Associate of Arts.
  6. author's alteration.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words

family, therapy, AA

Examples from the Web for aa

Contemporary Examples

Historical Examples

  • Lasst Midsummer Day aa was on t' Shanmoor road, i' t' gloaming.

    Robert Elsmere

    Mrs. Humphry Ward

  • IT is very difficult to give an all-round impression of aa man.

    The Good Soldier

    Ford Madox Ford

  • II was dreaming that I was caught in a trap, aa mousetrap, I think it was.

  • There were the footprints of the gamekeeper from A to his lodge at AA.

    The Canterbury Puzzles

    Henry Ernest Dudeney

  • But ther, you be 'ungry, and you aan't 'ad nothin' to ait for a long time.

    The Birthright

    Joseph Hocking

British Dictionary definitions for aa


  1. a volcanic rock consisting of angular blocks of lava with a very rough surface
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Word Origin



abbreviation for
  1. ana 1
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abbreviation for
  1. Alcoholics Anonymous
  2. anti-aircraft
  3. Architectural Association
  4. (in Britain) Automobile Association
  5. (in Britain) Advertising Association
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symbol for
  1. (in Britain, formerly) a film that may not be shown publicly to a child under fourteen
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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 aa


also AA, abbreviation of Alcoholics Anonymous, attested by 1941, American English. The group name was the title of a book published in 1938 by the founder, Bill W.

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Online Etymology Dictionary, © 2010 Douglas Harper

aa in Medicine


  1. Alcoholics Anonymous
  2. amino acid
  3. aminoacyl
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

aa in Science


  1. A type of lava having a rough, jagged surface. It is relatively slow moving in its molten state, advancing in the form of massive blocks with fissured and angular surfaces that ride on a viscous interior. The blocks range in size between the size of a football and the size of a house. See Note at pahoehoe.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.