(St.) or Mie Touche (Touch-me-not). A hypocrite, a demure-looking pharisee. The French say, Faire la Sainte Nitouche, to pretend to great sanctity, or look as if butter would not melt in your mouth.
“It is certainly difficult to believe hard things of a woman who looks like Ste. Nitouche in profile.” —J. O. Hobbes: Some Emotions and a Moral, chap. iii.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894