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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  

/ ˈɑːɑː /

noun

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

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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

Like stirring a cup of tea, mixing the lava sped up cooling—and seemingly triggered the formation of aa, says study author Cansu Culha, a postdoctoral fellow at the University of British Columbia.

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

"Doctor," said the Squire in a shaky voice, "we had aa better gang awa oot o' the room till the meetin's owre."

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

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

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

To recreate the original stuffed toy version of Roo, the baby kangaroo that appears in author AA Milne's Winnie-the-Pooh stories.

From BBC ● Apr. 29, 2026

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

From BBC ● Apr. 22, 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

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

From Salon ● Jun. 19, 2026

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

Though there are other characters — an A.A. sponsor; Kirsten’s stern father — Guettel chose to have only Kirsten, Joe and, occasionally, their daughter, sing.

From New York Times ● Jan. 22, 2024

The field meeting of the Conn. High-school A.A. on the Charter Oak track at Hartford next month promises to be one of the most interesting contests of the interscholastic season.

From Harper's Round Table, May 7, 1895 by Various