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• aa
  aa

  noun

  basaltic lava having a rough surface.
• AA
  AA

  abbreviation

  administrative assistant.
• a̅a̅
  a̅a̅

  (in prescriptions) ana.
• a.a.
  a.a.

  abbreviation

  author's alteration. Also A.A., AA
• A.A.
  A.A.

  abbreviation

  Alcoholics Anonymous.

aa

¹ American  

[ah-ah] / ˈɑ ɑ /

Or a'a,

noun

1. basaltic lava having a rough surface.

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AA ² American  

abbreviation

1. administrative assistant.

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AA ³ American  

Symbol.

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 inch (1.4 centimeters); length, 2 inches (5 centimeters).

5. British. a designation for motion pictures certified as unsuitable for children under 14 unless accompanied by an adult.

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a̅a̅ ⁴ American  

Or āa

Symbol.

1. (in prescriptions) ana.

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a.a. ⁵ American  

Or aa

abbreviation

1. author's alteration. Also A.A., AA

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A.A. ⁶ American  

[ay-ay] / ˈeɪˈeɪ /

Or AA

abbreviation

1. Alcoholics Anonymous.

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A.A. ⁷ American  

abbreviation

1. antiaircraft. Also AA

2. Associate in Accounting.

3. Associate of Arts.

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aa ¹ British  

/ ˈɑːɑː /

noun

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

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AA ² British  

abbreviation

1. Alcoholics Anonymous

2. anti-aircraft

3. Architectural Association

4. (in Britain) Automobile Association

5. (in Britain) Advertising Association

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symbol

1. (in Britain, formerly) a film that may not be shown publicly to a child under fourteen

aa ³ British  

abbreviation

1. ana ¹

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aa Scientific  

/ ä′ä /

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.

2. See Note at pahoehoe

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Etymology

Origin of aa¹

First recorded in 1855–60; from Hawaiian ʿaʿā

Origin of a̅a̅⁴

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

Example Sentences

See Examples For:

aa AA A.A.

Mr. Warsh is known as aa inflation hawk, which makes Mr. Trump’s nomination especially notable.

From The Wall Street Journal ● Jan. 30, 2026

Understanding how pahoehoe morphs into aa is more than just scientific curiosity because the two lava types move at different speeds and pose distinct hazards.

From Science Magazine ● Jun. 9, 2023

The two main types of basaltic volcanic rock have Hawaiian names—pahoehoe and aa.

From Textbooks ● Jan. 1, 2017

"Ranjish hee sahi," says one Facebook update, "dil hee dukhaane ke liye aa!"

From The Guardian ● Jun. 14, 2012

Then, meenister, see that ye aa tak' your revolvers and cartridges.

From Two Knapsacks A Novel of Canadian Summer Life by John Campbell

He brought it to the American baggage services office and called after tracking me down, probably by the AA frequent flier number on my new AA credit card I pulled out on the plane.

From The Wall Street Journal ● Sep. 18, 2026

This year marks the centenary of AA Milne's books, first published in 1926 and later brought to the screen by Walt Disney.

From BBC ● Jul. 7, 2026

Motoring group the AA said it expects pump prices to fall further and "the timing is perfect for the start of the summer holidays".

From BBC ● Jun. 19, 2026

Pothole-related incidents attended by The AA decreased in 2025 compared with 2024, although the organisation's statistics show the 68,786 incidents recorded in January this year were higher than any month last year.

From BBC ● May 4, 2026

Dad was already leafing through his AA Book of British Towns and Uncle Brian'd sent Mum a look that said, If it makes the old boy happy, let him.

From "Black Swan Green" by David Mitchell

“People are becoming a lot more cynical about the kind of rip-offs they’re facing,” said Samuel A.A.

From The Wall Street Journal ● Sep. 23, 2026

“Emancipation Day was usually the occasion of the beating of drums and the marching of militia,” wrote A.A.

From Salon ● Jun. 19, 2026

The beloved children's character ambled into the world in 1926 in a book written by English author A.A.

From Barron's ● Mar. 10, 2026

Sharon — the hairdresser, played by Hilary Swank — learns of Schmitt’s plight and decides to help the family as a focus for her energies after reluctantly attending an A.A. meeting.

From New York Times ● Feb. 22, 2024

This collection included a number of songs which have always been favorites, by Professor Gayley and Professor Fred N. Scott, '84, for which the music, in many cases, was written by Dr. A.A.

From The University of Michigan by Wilfred Shaw