[ law-guh-rith-uh m, -rith-, log-uh- ]
/ ˈlɔ gəˌrɪð əm, -ˌrɪθ-, ˈlɒg ə- /

noun Mathematics.

the exponent of the power to which a base number must be raised to equal a given number; log: 2 is the logarithm of 100 to the base 10 (2 = log10 100).

Nearby words

  1. logania family,
  2. loganiaceous,
  3. logansport,
  4. logaoedic,
  5. logaphasia,
  6. logarithmic,
  7. logarithmic function,
  8. logasthenia,
  9. logbook,
  10. loge

Origin of logarithm

1605–15; < New Latin logarithmus < Greek lóg(os) log- + arithmós number; see arithmetic

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for logarithm

British Dictionary definitions for logarithm


/ (ˈlɒɡəˌrɪðəm) /


the exponent indicating the power to which a fixed number, the base, must be raised to obtain a given number or variable. It is used esp to simplify multiplication and division: if a x = M, then the logarithm of M to the base a (written log a M) is xOften shortened to: log See also common logarithm, natural logarithm

Word Origin for logarithm

C17: from New Latin logarithmus, coined 1614 by John Napier, from Greek logos ratio, reckoning + arithmos number

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 logarithm



1610s, Modern Latin logarithmus, coined by Scottish mathematician John Napier (1550-1617), literally "ratio-number," from Greek logos "proportion, ratio, word" (see logos) + arithmos "number" (see arithmetic).

Online Etymology Dictionary, © 2010 Douglas Harper

Science definitions for logarithm


[ lôgə-rĭð′əm ]

The power to which a base must be raised to produce a given number. For example, if the base is 10, then the logarithm of 1,000 (written log 1,000 or log10 1,000) is 3 because 103 = 1,000. See more at common logarithm natural logarithm.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.