from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The 18th letter of the Greek alphabet. See Table at alphabet.
- n. A sigma factor.
- n. A sigma baryon.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The name for the eighteenth letter of the Classical and Modern Greek, the nineteenth letter of Old and Ancient.
- n. The symbol Σ, used to indicate summation of a set or series.
- n. The symbol σ, used to indicate one standard deviation from the mean, particularly in a normal distribution.
from the GNU version of the Collaborative International Dictionary of English
- n. The Greek letter Σ, σ, or ς (English S, or s). It originally had the form of the English C.
from The Century Dictionary and Cyclopedia
- n. The name of the Greek letter
Σ, σ, ς, equivalent to the English S, s. (For its early forms, see under S.)
- n. An S-shaped or sigmoid flesh-spicule of a sponge.
- n. The curve of the letter S or any approximate curve.
- n. In descriptive biol., one of the S-shaped ridges on the surface of certain molluscan shells, as those of gastropods and cephalopods.
- n. In experimental psychology, the time-unit, of a second: abbreviated
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the 18th letter of the Greek alphabet
Greek sīgma, of Phoenician origin; see smk in Semitic roots.(American Heritage® Dictionary of the English Language, Fourth Edition)