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  1. a natural manure composed chiefly of the excrement of sea birds, found especially on islands near the Peruvian coast.
  2. any similar substance, as an artificial fertilizer made from fish.

Origin of guano

1595–1605; < Spanish: fertilizer, dung; American Spanish huano dung < Quechua wanu dung for fuel, fertilizer
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for guano

Historical Examples

  • He was the man who said my browns were all put in with guano.

    Continental Monthly, Vol. III, No IV, April 1863


  • "I thought you gentlemen were in the guano business," says I, when he had finished.

  • The evidence in favor of guano in this case, needs no comment.


    Solon Robinson

  • This is not only the most valuable, but is found in the largest quantities of any other guano known.


    Solon Robinson

  • It will not do to put the guano in the hill and plant the corn upon it.


    Solon Robinson

British Dictionary definitions for guano


noun plural -nos
    1. the dried excrement of fish-eating sea birds, deposited in rocky coastal regions of South America: contains the urates, oxalates, and phosphates of ammonium and calcium; used as a fertilizer
    2. the accumulated droppings of bats and seals
  1. any similar but artificial substance used as a fertilizer

Word Origin

C17: from Spanish, from Quechuan huano dung
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for guano


c.1600, from Spanish guano "dung," especially of sea-birds on islands off Peru, from Quechua huanu "dung."

Online Etymology Dictionary, © 2010 Douglas Harper

guano in Science


  1. A substance composed chiefly of the dung of sea birds or bats, accumulated along certain coastal areas or in caves and used as fertilizer.
  2. Any of various similar substances, such as a fertilizer prepared from ground fish parts.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.