aa — English Dictionary

Noun

1. 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.

   Usage

   • Uncountable

   Examples

   We...saw ‘pahoihoi’ or solid lava forming, and also ‘aa’ or clinkers.

   Cooling and solidification frequently takes a different course [...] in lava flows, producing the clinker-like ‘aa’ lava.

   More examples (1)

   Both pahoehoe and aa lava flows are common on the upper slopes of Mauna Loa with a preponderance of aa flows found at the lower elevations.

Pronoun

1. I.

   Usage

   • Northumbria
   • personal

Noun

1. a dry form of lava resembling clinkers

   Broader terms

   lava