from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The fraction of incident electromagnetic radiation reflected by a surface, especially of a celestial body.
  • noun The spongy white tissue on the inside of the rind of citrus fruit.

from The Century Dictionary.

  • noun Whiteness; specifically, the proportion of light falling on a surface and irregularly reflected from it: as, the albedo of the moon.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Astron.) Whiteness.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun physics, meteorology, astronomy The fraction of incident light or radiation reflected by a surface or body, commonly expressed as percentage.
  • noun biology The whitish inner portion of the rind of citrus fruits that is a source of pectin, commonly referred to as the pith.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun the ratio of reflected to incident light


from The American Heritage® Dictionary of the English Language, 4th Edition

[Late Latin albēdō, whiteness, from Latin albus, white; see albho- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin albēdō ("whiteness").


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  • I was enjoying the book until I came across the following sentence: "The albedo of Gilgit's brown, barren hills is high, and the heat from the sun just seems to bounce around the bowl that the town sits in." James Meek

    January 3, 2008

  • Great article, brtom--thanks for posting this.

    January 3, 2008

  • Just for fun

    April 2, 2010

  • Some five years after learning it here, I finally spotted it in the wild in Ender’s Game. :-D

    October 14, 2013

  • "The answer is always the same: albedo."

    Mike Brown, How I Killed Pluto and Why It Had It Coming</i> (New York: Spiegel & Grau, 2010)

    October 11, 2015