Look up sigmoid in Wiktionary, the free dictionary.

Sigmoid means resembling the lower-case Greek letter sigma (uppercase Σ, lowercase σ, lowercase in word-final position ς) or the Latin letter S. Specific uses include:

• Sigmoid function, a mathematical function
• Sigmoid colon, part of the large intestine or colon
• Sigmoid sinus, two structures that drain blood from the bottom of the brain
• Sigmoid arteries, a pair/trio of arteries in the lower abdomen

See also

• Ogee, similar shape, term sometimes used for sigmoids