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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

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

An' aa saw theer t' bogle—thee knaws, t' bogle o' Bleacliff Tarn; an' she turned hersel, an' she spoak to me!'

From Robert Elsmere by Mrs. Humphry Ward

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

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

From BBC ● Jun. 26, 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

Love, AA I get my stitches out today.

From "Winger" by Andrew Smith

“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

The company also acquired rights to author A.A.

From Los Angeles Times ● Oct. 16, 2023

It is now in the possession of Mr. George H. Allan, who received it from his uncle, A.A.

From Tea Leaves Being a Collection of Letters and Documents relating to the shipment of Tea to the American Colonies in the year 1773, by the East India Tea Company. (With an introduction, notes, and biographical notices of the Boston Tea Party) by Francis S. (Francis Samuel) Drake