c. 1600 (in "Measure for Measure," with the disparaging sense "making a show of sanctity, affecting an appearance of holiness"), from sanctimony + -ous. The un-ironic, literal sense was used occasionally in English from c. 1600 to c. 1800. Related: Sanctimoniously; sanctimoniousness.
a sickening sanctimonious smile
san
San Francisco
sanatorium
sanctification
sanctify
sanctimonious
sanctimony
sanction
sanctions
sanctitude
sanctity