Sigmoid means resembling the lower-case Greek letter
sigma
Sigma ( ; uppercase Σ, lowercase σ, lowercase in word-final position ς; ) is the eighteenth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 200. In general mathematics, uppercase Σ is used as an operator ...
(
uppercase
Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''#Majuscule, majuscule'') and smaller lowercase (more formally ''#Minuscule, minuscule'') in the written representation of certain langua ...
Σ,
lowercase
Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''majuscule'') and smaller lowercase (more formally '' minuscule'') in the written representation of certain languages. The writing system ...
σ, lowercase in word-final position ς) or the Latin letter
S. Specific uses include:
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Sigmoid function
A sigmoid function is any mathematical function whose graph of a function, graph has a characteristic S-shaped or sigmoid curve.
A common example of a sigmoid function is the logistic function, which is defined by the formula
:\sigma(x ...
, a mathematical function
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Sigmoid colon
The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...
, part of the large intestine or colon
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Sigmoid sinus
The sigmoid sinuses (sigma- or s-shaped hollow curve), also known as the , are paired dural venous sinuses within the skull that receive blood from posterior transverse sinuses.
Structure
The sigmoid sinus is a dural venous sinus situated withi ...
, two structures that drain blood from the bottom of the brain
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Sigmoid arteries, a pair/trio of arteries in the lower abdomen
See also
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Ogee
An ogee ( ) is an object, element, or curve—often seen in architecture and building trades—that has a serpentine- or extended S-shape (Sigmoid curve, sigmoid). Ogees consist of a "double curve", the combination of two semicircle, semicircula ...
, similar shape, term sometimes used for sigmoids
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