[ sig-muh ]
/ ˈsɪg mə /


the 18th letter of the Greek alphabet: Σ, σ, ς.
the consonant sound represented by this letter.

Nearby words

  1. sigint,
  2. sigismund,
  3. sigismund ii,
  4. sigla,
  5. siglos,
  6. sigma baryon,
  7. sigma factor,
  8. sigma particle,
  9. sigmate,
  10. sigmation

Origin of sigma

1600–10; < Latin < Greek sígma Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for sigma

British Dictionary definitions for sigma


/ (ˈsɪɡmə) /


the 18th letter in the Greek alphabet (Σ, σ, or, when final, ς), a consonant, transliterated as S
maths the symbol Σ, indicating summation of the numbers or quantities indicated

Word Origin for sigma

Greek, of Semitic origin; related to Hebrew samekh

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 sigma


18th letter of the Greek alphabet, corresponding to Latin S, a metathesis of Hebrew samekh. In uncial writing, shaped like an S or a C.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for sigma


[ sĭgmə ]


The 18th letter of the Greek alphabet.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for sigma


[ sĭgmə ]

A sigma baryon.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.