| 释义 |
sig·ma
I. \ˈsigmə\ noun
(-s)
Etymology: Greek, of Semitic origin; akin to Hebrew sāmekh samekh
1. : the 18th letter of the Greek alphabet — symbol Σ or σ or ς; see alphabet tables; compare lunar sigma
2. : the thousandth part of a second : millisecond
3.
a. : standard deviation — symbol σ
b. : the sum of — symbol Σ
4. : a C-shaped sponge spicule
II. noun
or sigma particle
: an unstable subatomic particle of the baryon family existing in positive, negative, and neutral charge states with masses respectively 2328, 2343, and 2333 times the mass of an electron |