circumflex vs sigmoid

circumflex

adj
  • Curving around. 

  • Having a circumflex mark. 

noun
  • A diacritical mark (ˆ) placed over a vowel in the orthography or transliteration of many languages to change its pronunciation; while in some other languages over a consonant. 

verb
  • To mark or pronounce with a circumflex. 

sigmoid

adj
  • Curved in two directions, like the letter "S", or the Greek ς (sigma); having a serpentine shape. 

  • Relating to the sigmoid colon. 

  • Exhibiting logistic growth; having a graph that accelerates until it reaches a carrying capacity. 

How often have the words circumflex and sigmoid occurred in a corpus of books? (source: Google Ngram Viewer )