Main definitions of aa in English

: aa1AA2

aa1

noun

mass nounGeology
  • Basaltic lava forming very rough, jagged masses with a light frothy texture.

    Often contrasted with pahoehoe
    • ‘Very different from jagged aa, pahoehoe is the other general texture of newly solidified lava.’
    • ‘Roads of black ash traverse it, winding through the otherwise untraversable aa.’
    • ‘A serpentine flow meanders through formations of smooth pahoehoe lava and rough aa lava, the same forms common in basalt lavas.’

Origin

Mid 19th century: from Hawaiian 'a-'a.

Pronunciation

aa

/ˈɑːɑː/

Main definitions of aa in English

: aa1AA2

AA2

  • 1Alcoholics Anonymous.

  • 2Anti-aircraft.

  • 3(in the UK and South Africa) Automobile Association.

Pronunciation

AA

/eɪˈeɪ/