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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  

[ey-ey] / 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  

abbreviation

1. ana ¹

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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  

/ ˈɑːɑː /

noun

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

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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

The AA recorded 5,241 pothole-related incidents in Scotland in March, an increase of almost 8% on the previous month.

From BBC • May 14, 2026

The famous toy bear Winnie took its name from a black bear in London Zoo, that was particularly popular with children, including the son of AA Milne.

From BBC • Apr. 25, 2026

AA Milne created the much-loved bedtime stories - which were later made into a Disney cartoon - based on the collection of stuffed toys belonging to his son, Christopher Robin Milne.

From BBC • Apr. 25, 2026

Adaptive Abilities, or AA, is a category where cheerleaders with and without disabilities compete side-by-side.

From BBC • Apr. 22, 2026

AA 23:234: “For one quarter, Black Tiger lets me escape from my rotten existence for three glorious hours. Pretty good deal.”

From "Ready Player One: A Novel" by Ernest Cline