or a'a

[ ah-ah ]
/ ˈɑ ɑ /


basaltic lava having a rough surface.

Words nearby aa

Compare pahoehoe.

Origin of aa

First recorded in 1855–60, aa is from the Hawaiian word ʿaʿā

Definition for aa (2 of 6)

Definition for aa (3 of 6)



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 A(def 11), U(def 6), X(def 9).

Definition for aa (4 of 6)


or āa


(in prescriptions) ana2.

Origin of a̅a̅

From the Greek word aná, with superscript bar representing the nasal consonant

Definition for aa (5 of 6)

Definition for aa (6 of 6)


antiaircraft artillery.
Associate in Accounting.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for aa

British Dictionary definitions for aa (1 of 3)

/ (ˈɑːɑː) /


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

Word Origin for aa


British Dictionary definitions for aa (2 of 3)


abbreviation for

ana 1

British Dictionary definitions for aa (3 of 3)


abbreviation for

Alcoholics Anonymous
Architectural Association
(in Britain) Automobile Association
(in Britain) Advertising Association

symbol for

(in Britain, formerly) a film that may not be shown publicly to a child under fourteen
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for aa



Alcoholics Anonymous
amino acid
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for aa

[ ää ]

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.