Definition of "aa"

(volcanology) A form of lava flow associated with Hawaiian-type volcanoes, consisting of basaltic rock, usually dark-colored with a jagged and loose, clinkery surface. Compare pahoehoe.  quotations

Initialism of acetic acid.  examples

Initialism of acting age.  examples

(medicine) Initialism of alveolar-arterial.  examples

Initialism of aminoacetone.  examples

Initialism of amino acid.  examples

Initialism of approximate absolute.  examples

Initialism of arachidonic acid.  examples

Initialism of armature accelerator.  examples

Initialism of ascending aorta.  examples

Initialism of atomic absorption.  examples

Initialism of author's alteration.  examples

Initialism of average audience.  examples

Initialism of arctic-alpine.  examples

Initialism of always afloat.  examples

Abbreviation of adjectives.  examples

Abbreviation of arteries.  examples

Abbreviation of ana (“of each, equal parts”).  examples