Initialism of airborne. / Initialism of antiballistic. / (baseball) Initialism of at bat.

(informal, idiomatic) To hurry up, to get moving.

(music) A vocal performance with no instrumental accompaniment.

(music) In a manner of a choir with no instrumental accompaniment; literally, "in the style of the (Sistine) Chapel (in Rome)", such as a musical Mass done a cappella.

(music) Singing solely or mainly without instrumental accompaniment. / (music, US) Related to a form of purely vocal music mostly associated with American college performance groups.

(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.

Initialism of acetic acid. / Initialism of acting age. / (medicine) Initialism of alveolar-arterial. / Initialism of aminoacetone. / Initialism of amino acid. / Initialism of approximate absolute.

Initialism of arctic-alpine. / Initialism of always afloat.

Abbreviation of adjectives. / Abbreviation of arteries.

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