basaltic lava having a rough surface.
a proportional shoe width size, narrower than A and wider than AAA.
the smallest proportional brassiere cup size.
a quality rating for a corporate or municipal bond, lower than AAA and higher than A.
Electricity. a battery size for 1.5 volt dry cells: diameter, 0.6 inches (1.4 cm); length, 2 inches (5 cm).
British. a designation for motion pictures certified as unsuitable for children under 14 unless accompanied by an adult.
Compare (def 11), (def 5 ,) (def 9).
(in prescriptions) 2 .
antiaircraft artillery.
Associate in Accounting.
Contemporary Examples

One friend remembers him taking her to an aa meeting when she herself first got sober not long afterward.
NYPD: We Have Hoffman’s Diary Michael Daly February 4, 2014

Alcoholics Anonymous (aa) has operated in Tehran for a number of years.
Iran’s Drinking Problem IranWire August 15, 2014

To me, total secrecy about aa and overcoming addiction just exacerbates the problem.
‘Celebrity Rehab’ Counselor: Mindy McCready Won’t Be the Last Maer Roshan February 25, 2013

A copy of aa Today, an Alcoholics Anonymous publication, rested atop the bureau.
Football Great Bob Suffridge Wanders Through the End Zone of Life Paul Hemphill September 5, 2014

aa, pronounced “ah-aah,” is cindery lava, the word’s from Hawaii but you may find some in Java.
National Scrabble Day: A Poem So You’ll Know All 101 Two-Letter Words David Bukszpan April 12, 2013

Historical Examples

C or heavy linen thread “aa” make a little block of four strands of floss over four threads of the material.
The Library of Work and Play: Needlecraft Effie Archer Archer

In fig. 1, aa is the body of the lock, bb the bolt and cc the key.
Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 7 Various

A keen-bladed dissecting knife, thrown by aa, stuck out from his left breast.
Astounding Stories of Super-Science, December 1930 Various

aa is the board the resistance of which is to be determined.
Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 1 Various

Storm (n), maapischi̍a (aa separated; final a short and low).
Travels in the Interior of North America, 1832-1834, Part III (the Text Being Chapters XXVIII-XXXIII of the London Edition, 1843, and the Appendix a Combination of the Appendices of the London and German [Coblentz, 1839] Editions) Maximilian, Prinz von Wied

a volcanic rock consisting of angular blocks of lava with a very rough surface
Alcoholics Anonymous
Architectural Association
(in Britain) Automobile Association
(in Britain) Advertising Association
(in Britain, formerly) a film that may not be shown publicly to a child under fourteen

also AA, abbreviation of Alcoholics Anonymous, attested by 1941, American English. The group name was the title of a book published in 1938 by the founder, Bill W.

AA abbr.

Alcoholics Anonymous

amino acid


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. See Note at pahoehoe.


: an AA barrage


An antiaircraft weapon, or antiaircraft fire; ack-ack, flak (WWI)
Afar (language)
author’s alteration
Academy of Aphasia
Acts of the Apostles
administrative assistant
adverse action
Alcoa Inc.
Alcoholics Anonymous
Alzheimer’s Association
Armed Forces Americas (except Canada)
Associate in Arts
atomic absorption

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