sigma; Σ, σ, ς +

(Greek: the eighteenth letter of the Greek alphabet; Σ, σ [beginning of word], ς [end of word])

1. The 18th letter of the Greek alphabet, represented in the English alphabet as "s".
2. The symbol (σ) indicating the addition of the numbers or quantities indicated.
sigma factor
A protein component of RNA polymerase that determines the specific site on DNA where transcription begins.
Having the form of the Greek sigma or the letter "S".
Incorrect, difficult, or the too frequent use of the "s" sound.
1. Shaped like the Greek capital letter sigma (Σ), or like the letter "S".
2. A reference to the sigmoid flexure.
sigmoid colon, clon sigmoideum
1. The S-shaped part of the colon which lies in the pelvis, extending from the pelvic brim to the third segment of the sacrum, and is continuous above with the descending (or iliac) colon and below with the rectum.
2. The part of the colon that turns medially at the left iliac crest, between the descending colon and the rectum; shaped like the letter "S".
sigmoid flexure
A fold in the colon just above the rectum of the body.
Excision of the sigmoid colon (the portion of the colon that connects to the descending colon above and the rectum below).
Inflammation of the sigmoid colon.
A rigid or flexible endoscope with appropriate illumination for examining the sigmoid colon.
Inspection of the sigmoid colon through a sigmoidoscope.
The formation of an artificial opening from the body surface into the sigmoid colon and the opening produced by this procedure.

You can see all of the letters of the Greek Alphabet on this page.