aa

n.
Lava having a rough surface.

[Hawaiian 'a'ā, to burn, aa.]

(ah-ah)

noun
Lava having a rough surface.

Etymology
From Hawaiian, apparently from the sound one emits on walking barefoot over the jagged lava surface

Aa is one of the two kinds of lava typically found in Hawaiian volcanoes. The other kind is pahoehoe, one with a smooth, ropy surface. You can see their pictures at: volcanoes.usgs.gov/Products/Pglossary/aa.html volcanoes.usgs.gov/Products/Pglossary/pahoehoe.html.

Usage
"Aa has a surface that's broken into blocks with sharp, spiny projections." — Ian Skilling, Lavas and Life, The World & I (Washington, DC), Jul 1998.

"With so much to memorize, trying to recall that aa is a kind of solidified lava or that an ai is a three-toed sloth, would tax the brain unnecessarily. Mr. Keskaroonkul estimates he knows nearly 110,000 words, or nearly 70% of Webster's New World Dictionary, published by Merriam-Webster. In comparison, the average college graduate is said to have an active vocabulary of 10,000 to 15,000 words." — Joseph Pereira, Hard Scrabble: Thais Who Play Very Well Learn the Dictionary -- But Some Have No Idea at All What the Words Mean; Why Clutter Up the Mind?, The Wall Street Journal (New York), Jul 19, 1999.

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(1) (Auto Answer) See modem.

(2) (Double A) A common single-cell battery used in a myriad of devices from flashlights to electronic equipment of all variety. Like its triple A (AAA) cousin, it provides 1.5 volts of DC power. When used in series, the voltage is multiplied. For example, four AA batteries yield 6 volts.

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Hawaiian  /ah ah/  lava having a rough surface

Blocky, angular, and rough type of lava flow.

Headlamp Aa	a 29 aa
kenyan aa	sabian aa