the 18th letter of the Greek alphabet: Σ, σ, ς.
the consonant sound represented by this letter.
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
sigma sig·ma (sĭg’mə)
Symbol ς The 18th letter of the Greek alphabet.
A sigma baryon.
A scientific visual programming environment from NASA.
- Sigma factor
sigma factor n. A protein component of RNA polymerase that determines the specific site on DNA where transcription begins.
noun, Physics. 1. an unstable hyperon having positive, negative, or zero electric charge and strangeness −1. Symbol: Σ.
adjective 1. having the form of the Greek sigma or the letter S. adjective 1. shaped like the Greek letter sigma or the Roman S
noun 1. defective pronunciation of sibilant sounds.