• synonyms


  1. Mathematics. the decimal part of a common logarithm.Compare characteristic(def 3a).
  2. Obsolete. an addition of little or no importance, as to a literary work.
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Origin of mantissa

1860–65; < Latin, variant of mantisa addition, makeweight, said to be from Etruscan; logarithmic mantissa so called because it is additional to the characteristic or integral part (term introduced by H. Briggs)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for mantissa

Historical Examples

  • Linnæus, however, says that his plant came from India (Mantissa, p. 273).

    Origin of Cultivated Plants

    Alphonse De Candolle

  • The integral part of a logarithm is called the index or characteristic, and the fractional part the mantissa.

  • Mantissa Plantarum, generum editionis sextæ et specierum editionis secundæ.

  • Linnæus has described this plant minutely in his Mantissa Plant, so that no doubt remains of its being his maritimus.

  • Linnæus originally confounded it with a similar plant, the Draba alpina, a mistake since rectified in his Mantissa Plant.

British Dictionary definitions for mantissa


  1. the fractional part of a common logarithm representing the digits of the associated number but not its magnitudethe mantissa of 2.4771 is .4771 Compare characteristic (def. 2a)
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Word Origin

C17: from Latin: something added, of Etruscan origin
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 mantissa


decimal part of a logarithm, 1865, from Latin mantisa "a worthless addition, makeweight," perhaps a Gaulish word introduced into Latin via Etruscan (cf. Old Irish meit, Welsh maint "size").

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Online Etymology Dictionary, © 2010 Douglas Harper

mantissa in Science


  1. The part of a logarithm to the base ten that is to the right of the decimal point. For example, if 2.749 is a logarithm, .749 is the mantissa. Compare characteristic.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.