Sigmoidal
/sɪɡˈmɔɪ.dəl/noun
Having the shape of the Greek letter sigma, especially a curved or S-shaped form.
Did you know?The word ultimately invokes sigma, the Greek letter used in mathematics for summation, linking an ancient alphabetic sign with the modern language of curves, statistics, and probability.
Etymological Timeline
Proto-Sinaitic / Phoenician period
Semitic
samekh
“The name of a Semitic consonant-letter, traditionally associated with a support or prop; its exact connection to Greek sigma is historically debated.”
Ancient Greek
Greek
σίγμα (sigma)
“The name of the Greek letter Σ, σ, or ς.”
Late Antiquity
Greek
σιγμοειδής (sigmoeidēs)
“Sigma-shaped; resembling the form of the letter sigma.”
17th Century
New Latin
sigmoides
“Sigmoid or sigma-shaped, used in anatomical and scientific description.”
19th Century
English
sigmoid
“Curved like the letter S or Greek sigma, especially in anatomy and mathematics.”
19th–20th Century
English
sigmoidal
“Relating to or having a sigmoid shape.”