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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. 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 ² British  

abbreviation

1. ana ¹

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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

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

The analysis revealed that in many cases, changes in the environment, such as steepening slopes or increasing eruption rates, amplified the ripples, which could lead to runaway mixing—and the likely formation of aa.

From Science Magazine ● Jun. 9, 2023

Peterson, D. W. & Tilling, R. I. Transition of basaltic lava from pahoehoe to aa, Kilauea Volcano, Hawaii: Field observations and key factors - ScienceDirect.

From Textbooks ● Jan. 1, 2017

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

From The Guardian ● Jun. 14, 2012

My eyes Anapanapa, alohi mai ana ia'u Have seen the gleaming flashes Ke aa o Akua Nunu.

From Northern California, Oregon, and the Sandwich Islands by Nordhoff, Charles

The AA said it received 14% more callouts than usual on Thursday for broken-down vehicles.

From BBC ● Jun. 26, 2026

On the roads, the AA has said there will be gritters out on some roads to help in case surfaces soften or become sticky in the heat.

From BBC ● Jun. 22, 2026

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

“These cultic movements and AA can achieve dramatic and rapid transformation,” he says, speaking very broadly of religious movements.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel

Another fun fact: The New York Public Library has the original stuffed animals that belonged to A.A.

From The Wall Street Journal ● Apr. 27, 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

Wells also lists the men who died young in their line of work: A.A.

From Salon ● Jul. 17, 2024

In 1971, he formed a law partnership with Peter A.A.

From New York Times ● Feb. 2, 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 Shaw, Wilfred